Revert per-index collation version tracking feature.

Design problems were discovered in the handling of composite types and
record types that would cause some relevant versions not to be recorded.
Misgivings were also expressed about the use of the pg_depend catalog
for this purpose.  We're out of time for this release so we'll revert
and try again.

Commits reverted:

1bf946bd: Doc: Document known problem with Windows collation versions.
cf002008: Remove no-longer-relevant test case.
ef387bed: Fix bogus collation-version-recording logic.
0fb0a050: Hide internal error for pg_collation_actual_version(<bad OID>).
ff942057: Suppress "warning: variable 'collcollate' set but not used".
d50e3b1f: Fix assertion in collation version lookup.
f24b1569: Rethink extraction of collation dependencies.
257836a7: Track collation versions for indexes.
cd6f479e: Add pg_depend.refobjversion.
7d1297df: Remove pg_collation.collversion.

Discussion: https://postgr.es/m/CA%2BhUKGLhj5t1fcjqAu8iD9B3ixJtsTNqyCCD4V0aTO9kAKAjjA%40mail.gmail.com

47 files changed, 363 insertions, 1252 deletions

diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index 41093ea6aee..259cde33976 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -76,7 +76,6 @@
 #include "rewrite/rewriteRemove.h"
 #include "storage/lmgr.h"
 #include "utils/acl.h"
-#include "utils/builtins.h"
 #include "utils/fmgroids.h"
 #include "utils/guc.h"
 #include "utils/lsyscache.h"
@@ -436,84 +435,6 @@ performMultipleDeletions(const ObjectAddresses *objects,
 }
 
 /*
- * Call a function for all objects that 'object' depend on.  If the function
- * returns true, refobjversion will be updated in the catalog.
- */
-void
-visitDependenciesOf(const ObjectAddress *object,
-					VisitDependenciesOfCB callback,
-					void *userdata)
-{
-	Relation	depRel;
-	ScanKeyData key[3];
-	SysScanDesc scan;
-	HeapTuple	tup;
-	ObjectAddress otherObject;
-
-	ScanKeyInit(&key[0],
-				Anum_pg_depend_classid,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(object->classId));
-	ScanKeyInit(&key[1],
-				Anum_pg_depend_objid,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(object->objectId));
-	ScanKeyInit(&key[2],
-				Anum_pg_depend_objsubid,
-				BTEqualStrategyNumber, F_INT4EQ,
-				Int32GetDatum(object->objectSubId));
-
-	depRel = table_open(DependRelationId, RowExclusiveLock);
-	scan = systable_beginscan(depRel, DependDependerIndexId, true,
-							  NULL, 3, key);
-
-	while (HeapTupleIsValid(tup = systable_getnext(scan)))
-	{
-		Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(tup);
-		char	   *new_version;
-		Datum		depversion;
-		bool		isnull;
-
-		otherObject.classId = foundDep->refclassid;
-		otherObject.objectId = foundDep->refobjid;
-		otherObject.objectSubId = foundDep->refobjsubid;
-
-		depversion = heap_getattr(tup, Anum_pg_depend_refobjversion,
-								  RelationGetDescr(depRel), &isnull);
-
-		/* Does the callback want to update the version? */
-		if (callback(&otherObject,
-					 isnull ? NULL : TextDatumGetCString(depversion),
-					 &new_version,
-					 userdata))
-		{
-			Datum		values[Natts_pg_depend];
-			bool		nulls[Natts_pg_depend];
-			bool		replaces[Natts_pg_depend];
-
-			memset(values, 0, sizeof(values));
-			memset(nulls, false, sizeof(nulls));
-			memset(replaces, false, sizeof(replaces));
-
-			if (new_version)
-				values[Anum_pg_depend_refobjversion - 1] =
-					CStringGetTextDatum(new_version);
-			else
-				nulls[Anum_pg_depend_refobjversion - 1] = true;
-			replaces[Anum_pg_depend_refobjversion - 1] = true;
-
-			tup = heap_modify_tuple(tup, RelationGetDescr(depRel), values,
-									nulls, replaces);
-			CatalogTupleUpdate(depRel, &tup->t_self, tup);
-
-			heap_freetuple(tup);
-		}
-	}
-	systable_endscan(scan);
-	table_close(depRel, RowExclusiveLock);
-}
-
-/*
  * findDependentObjects - find all objects that depend on 'object'
  *
  * For every object that depends on the starting object, acquire a deletion
@@ -1640,38 +1561,6 @@ ReleaseDeletionLock(const ObjectAddress *object)
 }
 
 /*
- * Record dependencies on a list of collations, optionally with their current
- * version.
- */
-void
-recordDependencyOnCollations(ObjectAddress *myself,
-							 List *collations,
-							 bool record_version)
-{
-	ObjectAddresses *addrs;
-	ListCell   *lc;
-
-	if (list_length(collations) == 0)
-		return;
-
-	addrs = new_object_addresses();
-	foreach(lc, collations)
-	{
-		ObjectAddress referenced;
-
-		ObjectAddressSet(referenced, CollationRelationId, lfirst_oid(lc));
-
-		add_exact_object_address(&referenced, addrs);
-	}
-
-	eliminate_duplicate_dependencies(addrs);
-	recordMultipleDependencies(myself, addrs->refs, addrs->numrefs,
-							   DEPENDENCY_NORMAL, record_version);
-
-	free_object_addresses(addrs);
-}
-
-/*
  * recordDependencyOnExpr - find expression dependencies
  *
  * This is used to find the dependencies of rules, constraint expressions,
@@ -1705,10 +1594,8 @@ recordDependencyOnExpr(const ObjectAddress *depender,
 
 	/* And record 'em */
 	recordMultipleDependencies(depender,
-							   context.addrs->refs,
-							   context.addrs->numrefs,
-							   behavior,
-							   false);
+							   context.addrs->refs, context.addrs->numrefs,
+							   behavior);
 
 	free_object_addresses(context.addrs);
 }
@@ -1735,8 +1622,7 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 								Node *expr, Oid relId,
 								DependencyType behavior,
 								DependencyType self_behavior,
-								bool reverse_self,
-								bool record_version)
+								bool reverse_self)
 {
 	find_expr_references_context context;
 	RangeTblEntry rte;
@@ -1795,10 +1681,8 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 		/* Record the self-dependencies with the appropriate direction */
 		if (!reverse_self)
 			recordMultipleDependencies(depender,
-									   self_addrs->refs,
-									   self_addrs->numrefs,
-									   self_behavior,
-									   record_version);
+									   self_addrs->refs, self_addrs->numrefs,
+									   self_behavior);
 		else
 		{
 			/* Can't use recordMultipleDependencies, so do it the hard way */
@@ -1817,10 +1701,8 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 
 	/* Record the external dependencies */
 	recordMultipleDependencies(depender,
-							   context.addrs->refs,
-							   context.addrs->numrefs,
-							   behavior,
-							   record_version);
+							   context.addrs->refs, context.addrs->numrefs,
+							   behavior);
 
 	free_object_addresses(context.addrs);
 }
@@ -1835,17 +1717,8 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
  * the datatype.  However we do need a type dependency if there is no such
  * indirect dependency, as for example in Const and CoerceToDomain nodes.
  *
- * Collations are handled primarily by recording the inputcollid's of node
- * types that have them, as those are the ones that are semantically
- * significant during expression evaluation.  We also record the collation of
- * CollateExpr nodes, since those will be needed to print such nodes even if
- * they don't really affect semantics.  Collations of leaf nodes such as Vars
- * can be ignored on the grounds that if they're not default, they came from
- * the referenced object (e.g., a table column), so the dependency on that
- * object is enough.  (Note: in a post-const-folding expression tree, a
- * CollateExpr's collation could have been absorbed into a Const or
- * RelabelType node.  While ruleutils.c prints such collations for clarity,
- * we may ignore them here as they have no semantic effect.)
+ * Similarly, we don't need to create dependencies on collations except where
+ * the collation is being freshly introduced to the expression.
  */
 static bool
 find_expr_references_walker(Node *node,
@@ -1907,6 +1780,17 @@ find_expr_references_walker(Node *node,
 						   context->addrs);
 
 		/*
+		 * We must also depend on the constant's collation: it could be
+		 * different from the datatype's, if a CollateExpr was const-folded to
+		 * a simple constant.  However we can save work in the most common
+		 * case where the collation is "default", since we know that's pinned.
+		 */
+		if (OidIsValid(con->constcollid) &&
+			con->constcollid != DEFAULT_COLLATION_OID)
+			add_object_address(OCLASS_COLLATION, con->constcollid, 0,
+							   context->addrs);
+
+		/*
 		 * If it's a regclass or similar literal referring to an existing
 		 * object, add a reference to that object.  (Currently, only the
 		 * regclass and regconfig cases have any likely use, but we may as
@@ -1990,6 +1874,11 @@ find_expr_references_walker(Node *node,
 		/* A parameter must depend on the parameter's datatype */
 		add_object_address(OCLASS_TYPE, param->paramtype, 0,
 						   context->addrs);
+		/* and its collation, just as for Consts */
+		if (OidIsValid(param->paramcollid) &&
+			param->paramcollid != DEFAULT_COLLATION_OID)
+			add_object_address(OCLASS_COLLATION, param->paramcollid, 0,
+							   context->addrs);
 	}
 	else if (IsA(node, FuncExpr))
 	{
@@ -1997,9 +1886,6 @@ find_expr_references_walker(Node *node,
 
 		add_object_address(OCLASS_PROC, funcexpr->funcid, 0,
 						   context->addrs);
-		if (OidIsValid(funcexpr->inputcollid))
-			add_object_address(OCLASS_COLLATION, funcexpr->inputcollid, 0,
-							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, OpExpr))
@@ -2008,9 +1894,6 @@ find_expr_references_walker(Node *node,
 
 		add_object_address(OCLASS_OPERATOR, opexpr->opno, 0,
 						   context->addrs);
-		if (OidIsValid(opexpr->inputcollid))
-			add_object_address(OCLASS_COLLATION, opexpr->inputcollid, 0,
-							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, DistinctExpr))
@@ -2019,9 +1902,6 @@ find_expr_references_walker(Node *node,
 
 		add_object_address(OCLASS_OPERATOR, distinctexpr->opno, 0,
 						   context->addrs);
-		if (OidIsValid(distinctexpr->inputcollid))
-			add_object_address(OCLASS_COLLATION, distinctexpr->inputcollid, 0,
-							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, NullIfExpr))
@@ -2030,9 +1910,6 @@ find_expr_references_walker(Node *node,
 
 		add_object_address(OCLASS_OPERATOR, nullifexpr->opno, 0,
 						   context->addrs);
-		if (OidIsValid(nullifexpr->inputcollid))
-			add_object_address(OCLASS_COLLATION, nullifexpr->inputcollid, 0,
-							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, ScalarArrayOpExpr))
@@ -2041,9 +1918,6 @@ find_expr_references_walker(Node *node,
 
 		add_object_address(OCLASS_OPERATOR, opexpr->opno, 0,
 						   context->addrs);
-		if (OidIsValid(opexpr->inputcollid))
-			add_object_address(OCLASS_COLLATION, opexpr->inputcollid, 0,
-							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, Aggref))
@@ -2052,9 +1926,6 @@ find_expr_references_walker(Node *node,
 
 		add_object_address(OCLASS_PROC, aggref->aggfnoid, 0,
 						   context->addrs);
-		if (OidIsValid(aggref->inputcollid))
-			add_object_address(OCLASS_COLLATION, aggref->inputcollid, 0,
-							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, WindowFunc))
@@ -2063,9 +1934,6 @@ find_expr_references_walker(Node *node,
 
 		add_object_address(OCLASS_PROC, wfunc->winfnoid, 0,
 						   context->addrs);
-		if (OidIsValid(wfunc->inputcollid))
-			add_object_address(OCLASS_COLLATION, wfunc->inputcollid, 0,
-							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, SubscriptingRef))
@@ -2110,6 +1978,11 @@ find_expr_references_walker(Node *node,
 		else
 			add_object_address(OCLASS_TYPE, fselect->resulttype, 0,
 							   context->addrs);
+		/* the collation might not be referenced anywhere else, either */
+		if (OidIsValid(fselect->resultcollid) &&
+			fselect->resultcollid != DEFAULT_COLLATION_OID)
+			add_object_address(OCLASS_COLLATION, fselect->resultcollid, 0,
+							   context->addrs);
 	}
 	else if (IsA(node, FieldStore))
 	{
@@ -2136,6 +2009,11 @@ find_expr_references_walker(Node *node,
 		/* since there is no function dependency, need to depend on type */
 		add_object_address(OCLASS_TYPE, relab->resulttype, 0,
 						   context->addrs);
+		/* the collation might not be referenced anywhere else, either */
+		if (OidIsValid(relab->resultcollid) &&
+			relab->resultcollid != DEFAULT_COLLATION_OID)
+			add_object_address(OCLASS_COLLATION, relab->resultcollid, 0,
+							   context->addrs);
 	}
 	else if (IsA(node, CoerceViaIO))
 	{
@@ -2144,6 +2022,11 @@ find_expr_references_walker(Node *node,
 		/* since there is no exposed function, need to depend on type */
 		add_object_address(OCLASS_TYPE, iocoerce->resulttype, 0,
 						   context->addrs);
+		/* the collation might not be referenced anywhere else, either */
+		if (OidIsValid(iocoerce->resultcollid) &&
+			iocoerce->resultcollid != DEFAULT_COLLATION_OID)
+			add_object_address(OCLASS_COLLATION, iocoerce->resultcollid, 0,
+							   context->addrs);
 	}
 	else if (IsA(node, ArrayCoerceExpr))
 	{
@@ -2152,6 +2035,11 @@ find_expr_references_walker(Node *node,
 		/* as above, depend on type */
 		add_object_address(OCLASS_TYPE, acoerce->resulttype, 0,
 						   context->addrs);
+		/* the collation might not be referenced anywhere else, either */
+		if (OidIsValid(acoerce->resultcollid) &&
+			acoerce->resultcollid != DEFAULT_COLLATION_OID)
+			add_object_address(OCLASS_COLLATION, acoerce->resultcollid, 0,
+							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, ConvertRowtypeExpr))
@@ -2191,24 +2079,6 @@ find_expr_references_walker(Node *node,
 			add_object_address(OCLASS_OPFAMILY, lfirst_oid(l), 0,
 							   context->addrs);
 		}
-		foreach(l, rcexpr->inputcollids)
-		{
-			Oid			inputcollid = lfirst_oid(l);
-
-			if (OidIsValid(inputcollid))
-				add_object_address(OCLASS_COLLATION, inputcollid, 0,
-								   context->addrs);
-		}
-		/* fall through to examine arguments */
-	}
-	else if (IsA(node, MinMaxExpr))
-	{
-		MinMaxExpr *mmexpr = (MinMaxExpr *) node;
-
-		/* minmaxtype will match one of the inputs, so no need to record it */
-		if (OidIsValid(mmexpr->inputcollid))
-			add_object_address(OCLASS_COLLATION, mmexpr->inputcollid, 0,
-							   context->addrs);
 		/* fall through to examine arguments */
 	}
 	else if (IsA(node, CoerceToDomain))
@@ -2255,7 +2125,8 @@ find_expr_references_walker(Node *node,
 		if (OidIsValid(wc->endInRangeFunc))
 			add_object_address(OCLASS_PROC, wc->endInRangeFunc, 0,
 							   context->addrs);
-		if (OidIsValid(wc->inRangeColl))
+		if (OidIsValid(wc->inRangeColl) &&
+			wc->inRangeColl != DEFAULT_COLLATION_OID)
 			add_object_address(OCLASS_COLLATION, wc->inRangeColl, 0,
 							   context->addrs);
 		/* fall through to examine substructure */
@@ -2415,7 +2286,7 @@ find_expr_references_walker(Node *node,
 		{
 			Oid			collid = lfirst_oid(ct);
 
-			if (OidIsValid(collid))
+			if (OidIsValid(collid) && collid != DEFAULT_COLLATION_OID)
 				add_object_address(OCLASS_COLLATION, collid, 0,
 								   context->addrs);
 		}
@@ -2437,7 +2308,7 @@ find_expr_references_walker(Node *node,
 		{
 			Oid			collid = lfirst_oid(ct);
 
-			if (OidIsValid(collid))
+			if (OidIsValid(collid) && collid != DEFAULT_COLLATION_OID)
 				add_object_address(OCLASS_COLLATION, collid, 0,
 								   context->addrs);
 		}
@@ -2834,8 +2705,7 @@ record_object_address_dependencies(const ObjectAddress *depender,
 	eliminate_duplicate_dependencies(referenced);
 	recordMultipleDependencies(depender,
 							   referenced->refs, referenced->numrefs,
-							   behavior,
-							   false);
+							   behavior);
 }
 
 /*
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 42ff175bc80..431e62e3897 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -2357,7 +2357,7 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 		 */
 		recordDependencyOnSingleRelExpr(&colobject, expr, RelationGetRelid(rel),
 										DEPENDENCY_AUTO,
-										DEPENDENCY_AUTO, false, false);
+										DEPENDENCY_AUTO, false);
 	}
 	else
 	{
@@ -2367,7 +2367,7 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 		 */
 		recordDependencyOnSingleRelExpr(&defobject, expr, RelationGetRelid(rel),
 										DEPENDENCY_NORMAL,
-										DEPENDENCY_NORMAL, false, false);
+										DEPENDENCY_NORMAL, false);
 	}
 
 	/*
@@ -3729,8 +3729,7 @@ StorePartitionKey(Relation rel,
 										RelationGetRelid(rel),
 										DEPENDENCY_NORMAL,
 										DEPENDENCY_INTERNAL,
-										true /* reverse the self-deps */ ,
-										false /* don't track versions */ );
+										true /* reverse the self-deps */ );
 
 	/*
 	 * We must invalidate the relcache so that the next
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index a628b3281ce..8ded2b53d4c 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -54,7 +54,6 @@
 #include "catalog/pg_trigger.h"
 #include "catalog/pg_type.h"
 #include "catalog/storage.h"
-#include "commands/defrem.h"
 #include "commands/event_trigger.h"
 #include "commands/progress.h"
 #include "commands/tablecmds.h"
@@ -78,7 +77,6 @@
 #include "utils/guc.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
-#include "utils/pg_locale.h"
 #include "utils/memutils.h"
 #include "utils/pg_rusage.h"
 #include "utils/rel.h"
@@ -1034,8 +1032,6 @@ index_create(Relation heapRelation,
 		ObjectAddress myself,
 					referenced;
 		ObjectAddresses *addrs;
-		List	   *colls = NIL,
-				   *colls_no_version = NIL;
 
 		ObjectAddressSet(myself, RelationRelationId, indexRelationId);
 
@@ -1119,65 +1115,30 @@ index_create(Relation heapRelation,
 			recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_SEC);
 		}
 
-		/* Get dependencies on collations for all index keys. */
-		for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
-		{
-			Oid			colloid = collationObjectId[i];
+		/* placeholder for normal dependencies */
+		addrs = new_object_addresses();
 
-			if (OidIsValid(colloid))
-			{
-				Oid			opclass = classObjectId[i];
+		/* Store dependency on collations */
 
-				/*
-				 * The *_pattern_ops opclasses are special: they explicitly do
-				 * not depend on collation order so we can save some effort.
-				 *
-				 * XXX With more analysis, we could also skip version tracking
-				 * for some cases like hash indexes with deterministic
-				 * collations, because they will never need to order strings.
-				 */
-				if (opclass == TEXT_BTREE_PATTERN_OPS_OID ||
-					opclass == VARCHAR_BTREE_PATTERN_OPS_OID ||
-					opclass == BPCHAR_BTREE_PATTERN_OPS_OID)
-					colls_no_version = lappend_oid(colls_no_version, colloid);
-				else
-					colls = lappend_oid(colls, colloid);
-			}
-			else
+		/* The default collation is pinned, so don't bother recording it */
+		for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
+		{
+			if (OidIsValid(collationObjectId[i]) &&
+				collationObjectId[i] != DEFAULT_COLLATION_OID)
 			{
-				Form_pg_attribute att = TupleDescAttr(indexTupDesc, i);
-
-				Assert(i < indexTupDesc->natts);
-
-				/*
-				 * Even though there is no top-level collation, there may be
-				 * collations affecting ordering inside types, so look there
-				 * too.
-				 */
-				colls = list_concat(colls, GetTypeCollations(att->atttypid));
+				ObjectAddressSet(referenced, CollationRelationId,
+								 collationObjectId[i]);
+				add_exact_object_address(&referenced, addrs);
 			}
 		}
 
-		/*
-		 * If we have anything in both lists, keep just the versioned one to
-		 * avoid some duplication.
-		 */
-		if (colls_no_version != NIL && colls != NIL)
-			colls_no_version = list_difference_oid(colls_no_version, colls);
-
-		/* Store the versioned and unversioned collation dependencies. */
-		if (colls_no_version != NIL)
-			recordDependencyOnCollations(&myself, colls_no_version, false);
-		if (colls != NIL)
-			recordDependencyOnCollations(&myself, colls, true);
-
 		/* Store dependency on operator classes */
-		addrs = new_object_addresses();
 		for (i = 0; i < indexInfo->ii_NumIndexKeyAttrs; i++)
 		{
 			ObjectAddressSet(referenced, OperatorClassRelationId, classObjectId[i]);
 			add_exact_object_address(&referenced, addrs);
 		}
+
 		record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL);
 		free_object_addresses(addrs);
 
@@ -1188,7 +1149,7 @@ index_create(Relation heapRelation,
 											(Node *) indexInfo->ii_Expressions,
 											heapRelationId,
 											DEPENDENCY_NORMAL,
-											DEPENDENCY_AUTO, false, true);
+											DEPENDENCY_AUTO, false);
 		}
 
 		/* Store dependencies on anything mentioned in predicate */
@@ -1198,7 +1159,7 @@ index_create(Relation heapRelation,
 											(Node *) indexInfo->ii_Predicate,
 											heapRelationId,
 											DEPENDENCY_NORMAL,
-											DEPENDENCY_AUTO, false, true);
+											DEPENDENCY_AUTO, false);
 		}
 	}
 	else
@@ -1277,130 +1238,6 @@ index_create(Relation heapRelation,
 	return indexRelationId;
 }
 
-typedef struct do_collation_version_check_context
-{
-	Oid			relid;
-	List	   *warned_colls;
-} do_collation_version_check_context;
-
-/*
- * Raise a warning if the recorded and current collation version don't match.
- * This is a callback for visitDependenciesOf().
- */
-static bool
-do_collation_version_check(const ObjectAddress *otherObject,
-						   const char *version,
-						   char **new_version,
-						   void *data)
-{
-	do_collation_version_check_context *context = data;
-	char	   *current_version;
-
-	/* We only care about dependencies on collations with a version. */
-	if (!version || otherObject->classId != CollationRelationId)
-		return false;
-
-	/* Ask the provider for the current version.  Give up if unsupported. */
-	current_version = get_collation_version_for_oid(otherObject->objectId,
-													false);
-	if (!current_version)
-		return false;
-
-	/*
-	 * We don't expect too many duplicates, but it's possible, and we don't
-	 * want to generate duplicate warnings.
-	 */
-	if (list_member_oid(context->warned_colls, otherObject->objectId))
-		return false;
-
-	/* Do they match? */
-	if (strcmp(current_version, version) != 0)
-	{
-		/*
-		 * The version has changed, probably due to an OS/library upgrade or
-		 * streaming replication between different OS/library versions.
-		 */
-		ereport(WARNING,
-				(errmsg("index \"%s\" depends on collation \"%s\" version \"%s\", but the current version is \"%s\"",
-						get_rel_name(context->relid),
-						get_collation_name(otherObject->objectId),
-						version,
-						current_version),
-				 errdetail("The index may be corrupted due to changes in sort order."),
-				 errhint("REINDEX to avoid the risk of corruption.")));
-
-		/* Remember not to complain about this collation again. */
-		context->warned_colls = lappend_oid(context->warned_colls,
-											otherObject->objectId);
-	}
-
-	return false;
-}
-
-/* index_check_collation_versions
- *		Check the collation version for all dependencies on the given index.
- */
-void
-index_check_collation_versions(Oid relid)
-{
-	do_collation_version_check_context context;
-	ObjectAddress object;
-
-	/*
-	 * The callback needs the relid for error messages, and some scratch space
-	 * to avoid duplicate warnings.
-	 */
-	context.relid = relid;
-	context.warned_colls = NIL;
-
-	object.classId = RelationRelationId;
-	object.objectId = relid;
-	object.objectSubId = 0;
-
-	visitDependenciesOf(&object, &do_collation_version_check, &context);
-
-	list_free(context.warned_colls);
-}
-
-/*
- * Update the version for collations.  A callback for visitDependenciesOf().
- */
-static bool
-do_collation_version_update(const ObjectAddress *otherObject,
-							const char *version,
-							char **new_version,
-							void *data)
-{
-	Oid		   *coll = data;
-
-	/* We only care about dependencies on collations with versions. */
-	if (!version || otherObject->classId != CollationRelationId)
-		return false;
-
-	/* If we're only trying to update one collation, skip others. */
-	if (OidIsValid(*coll) && otherObject->objectId != *coll)
-		return false;
-
-	*new_version = get_collation_version_for_oid(otherObject->objectId, false);
-
-	return true;
-}
-
-/*
- * Record the current versions of one or all collations that an index depends
- * on.  InvalidOid means all.
- */
-void
-index_update_collation_versions(Oid relid, Oid coll)
-{
-	ObjectAddress object;
-
-	object.classId = RelationRelationId;
-	object.objectId = relid;
-	object.objectSubId = 0;
-	visitDependenciesOf(&object, &do_collation_version_update, &coll);
-}
-
 /*
  * index_concurrently_create_copy
  *
@@ -1864,10 +1701,6 @@ index_concurrently_swap(Oid newIndexId, Oid oldIndexId, const char *oldName)
 	changeDependenciesOf(RelationRelationId, oldIndexId, newIndexId);
 	changeDependenciesOn(RelationRelationId, oldIndexId, newIndexId);
 
-	/* Now we have the old index's collation versions, so fix that. */
-	CommandCounterIncrement();
-	index_update_collation_versions(newIndexId, InvalidOid);
-
 	/*
 	 * Copy over statistics from old to new index
 	 */
@@ -3921,9 +3754,6 @@ reindex_index(Oid indexId, bool skip_constraint_checks, char persistence,
 	/* Close rels, but keep locks */
 	index_close(iRel, NoLock);
 	table_close(heapRelation, NoLock);
-
-	/* Record the current versions of all depended-on collations. */
-	index_update_collation_versions(indexId, InvalidOid);
 }
 
 /*
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 40d98a334a6..19068b652a0 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -49,6 +49,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
+				const char *collversion,
 				bool if_not_exists,
 				bool quiet)
 {
@@ -166,6 +167,10 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
 	namestrcpy(&name_ctype, collctype);
 	values[Anum_pg_collation_collctype - 1] = NameGetDatum(&name_ctype);
+	if (collversion)
+		values[Anum_pg_collation_collversion - 1] = CStringGetTextDatum(collversion);
+	else
+		nulls[Anum_pg_collation_collversion - 1] = true;
 
 	tup = heap_form_tuple(tupDesc, values, nulls);
 
diff --git a/src/backend/catalog/pg_constraint.c b/src/backend/catalog/pg_constraint.c
index 0081558c48a..a4e890020ff 100644
--- a/src/backend/catalog/pg_constraint.c
+++ b/src/backend/catalog/pg_constraint.c
@@ -362,7 +362,7 @@ CreateConstraintEntry(const char *constraintName,
 		 */
 		recordDependencyOnSingleRelExpr(&conobject, conExpr, relId,
 										DEPENDENCY_NORMAL,
-										DEPENDENCY_NORMAL, false, true);
+										DEPENDENCY_NORMAL, false);
 	}
 
 	/* Post creation hook for new constraint */
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index 1217c01b8ae..54688094f58 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -19,16 +19,13 @@
 #include "access/table.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
-#include "catalog/pg_collation.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_extension.h"
 #include "commands/extension.h"
 #include "miscadmin.h"
-#include "utils/builtins.h"
 #include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
-#include "utils/pg_locale.h"
 #include "utils/rel.h"
 
 
@@ -47,24 +44,18 @@ recordDependencyOn(const ObjectAddress *depender,
 				   const ObjectAddress *referenced,
 				   DependencyType behavior)
 {
-	recordMultipleDependencies(depender, referenced, 1, behavior, false);
+	recordMultipleDependencies(depender, referenced, 1, behavior);
 }
 
 /*
  * Record multiple dependencies (of the same kind) for a single dependent
  * object.  This has a little less overhead than recording each separately.
- *
- * If record_version is true, then a record is added even if the referenced
- * object is pinned, and the dependency version will be retrieved according to
- * the referenced object kind.  For now, only collation version is
- * supported.
  */
 void
 recordMultipleDependencies(const ObjectAddress *depender,
 						   const ObjectAddress *referenced,
 						   int nreferenced,
-						   DependencyType behavior,
-						   bool record_version)
+						   DependencyType behavior)
 {
 	Relation	dependDesc;
 	CatalogIndexState indstate;
@@ -103,30 +94,12 @@ recordMultipleDependencies(const ObjectAddress *depender,
 	slot_init_count = 0;
 	for (i = 0; i < nreferenced; i++, referenced++)
 	{
-		char	   *version = NULL;
-
-		if (record_version)
-		{
-			/* For now we only know how to deal with collations. */
-			if (referenced->classId == CollationRelationId)
-			{
-				/* These are unversioned, so don't waste cycles on them. */
-				if (referenced->objectId == C_COLLATION_OID ||
-					referenced->objectId == POSIX_COLLATION_OID)
-					continue;
-
-				version = get_collation_version_for_oid(referenced->objectId,
-														false);
-			}
-		}
-
 		/*
 		 * If the referenced object is pinned by the system, there's no real
-		 * need to record dependencies on it, unless we need to record a
-		 * version.  This saves lots of space in pg_depend, so it's worth the
-		 * time taken to check.
+		 * need to record dependencies on it.  This saves lots of space in
+		 * pg_depend, so it's worth the time taken to check.
 		 */
-		if (version == NULL && isObjectPinned(referenced, dependDesc))
+		if (isObjectPinned(referenced, dependDesc))
 			continue;
 
 		if (slot_init_count < max_slots)
@@ -142,9 +115,6 @@ recordMultipleDependencies(const ObjectAddress *depender,
 		 * Record the dependency.  Note we don't bother to check for duplicate
 		 * dependencies; there's no harm in them.
 		 */
-		memset(slot[slot_stored_count]->tts_isnull, false,
-			   slot[slot_stored_count]->tts_tupleDescriptor->natts * sizeof(bool));
-
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_refclassid - 1] = ObjectIdGetDatum(referenced->classId);
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_refobjid - 1] = ObjectIdGetDatum(referenced->objectId);
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_refobjsubid - 1] = Int32GetDatum(referenced->objectSubId);
@@ -152,10 +122,9 @@ recordMultipleDependencies(const ObjectAddress *depender,
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_classid - 1] = ObjectIdGetDatum(depender->classId);
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_objid - 1] = ObjectIdGetDatum(depender->objectId);
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_objsubid - 1] = Int32GetDatum(depender->objectSubId);
-		if (version)
-			slot[slot_stored_count]->tts_values[Anum_pg_depend_refobjversion - 1] = CStringGetTextDatum(version);
-		else
-			slot[slot_stored_count]->tts_isnull[Anum_pg_depend_refobjversion - 1] = true;
+
+		memset(slot[slot_stored_count]->tts_isnull, false,
+			   slot[slot_stored_count]->tts_tupleDescriptor->natts * sizeof(bool));
 
 		ExecStoreVirtualTuple(slot[slot_stored_count]);
 		slot_stored_count++;
diff --git a/src/backend/catalog/pg_type.c b/src/backend/catalog/pg_type.c
index dc9d28a32c5..da65584476b 100644
--- a/src/backend/catalog/pg_type.c
+++ b/src/backend/catalog/pg_type.c
@@ -15,7 +15,6 @@
 #include "postgres.h"
 
 #include "access/htup_details.h"
-#include "access/relation.h"
 #include "access/table.h"
 #include "access/xact.h"
 #include "catalog/binary_upgrade.h"
@@ -521,74 +520,6 @@ TypeCreate(Oid newTypeOid,
 }
 
 /*
- * Get a list of all distinct collations that the given type depends on.
- */
-List *
-GetTypeCollations(Oid typeoid)
-{
-	List	   *result = NIL;
-	HeapTuple	tuple;
-	Form_pg_type typeTup;
-
-	tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typeoid));
-	if (!HeapTupleIsValid(tuple))
-		elog(ERROR, "cache lookup failed for type %u", typeoid);
-	typeTup = (Form_pg_type) GETSTRUCT(tuple);
-
-	/*
-	 * If the type has a typcollation attribute, report that and we're done.
-	 * Otherwise, it could be a container type that we should recurse into.
-	 */
-	if (OidIsValid(typeTup->typcollation))
-		result = list_make1_oid(typeTup->typcollation);
-	else if (typeTup->typtype == TYPTYPE_COMPOSITE)
-	{
-		Relation	rel = relation_open(typeTup->typrelid, AccessShareLock);
-		TupleDesc	desc = RelationGetDescr(rel);
-
-		for (int i = 0; i < RelationGetNumberOfAttributes(rel); i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(desc, i);
-
-			if (att->attisdropped)
-				continue;
-			if (OidIsValid(att->attcollation))
-				result = list_append_unique_oid(result, att->attcollation);
-			else
-				result = list_concat_unique_oid(result,
-												GetTypeCollations(att->atttypid));
-		}
-
-		relation_close(rel, NoLock);
-	}
-	else if (typeTup->typtype == TYPTYPE_DOMAIN)
-	{
-		Assert(OidIsValid(typeTup->typbasetype));
-		result = GetTypeCollations(typeTup->typbasetype);
-	}
-	else if (typeTup->typtype == TYPTYPE_RANGE)
-	{
-		Oid			rangecoll = get_range_collation(typeTup->oid);
-
-		if (OidIsValid(rangecoll))
-			result = list_make1_oid(rangecoll);
-		else
-		{
-			Oid			rangeid = get_range_subtype(typeTup->oid);
-
-			Assert(OidIsValid(rangeid));
-			result = GetTypeCollations(rangeid);
-		}
-	}
-	else if (IsTrueArrayType(typeTup))
-		result = GetTypeCollations(typeTup->typelem);
-
-	ReleaseSysCache(tuple);
-
-	return result;
-}
-
-/*
  * GenerateTypeDependencies: build the dependencies needed for a type
  *
  * Most of what this function needs to know about the type is passed as the
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index b8ec6f57564..ebb0994db32 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -62,12 +62,14 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
 	DefElem    *deterministicEl = NULL;
+	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
 	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
+	char	   *collversion = NULL;
 	Oid			newoid;
 	ObjectAddress address;
 
@@ -95,6 +97,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &providerEl;
 		else if (strcmp(defel->defname, "deterministic") == 0)
 			defelp = &deterministicEl;
+		else if (strcmp(defel->defname, "version") == 0)
+			defelp = &versionEl;
 		else
 		{
 			ereport(ERROR,
@@ -163,6 +167,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (deterministicEl)
 		collisdeterministic = defGetBoolean(deterministicEl);
 
+	if (versionEl)
+		collversion = defGetString(versionEl);
+
 	if (collproviderstr)
 	{
 		if (pg_strcasecmp(collproviderstr, "icu") == 0)
@@ -209,6 +216,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		}
 	}
 
+	if (!collversion)
+		collversion = get_collation_actual_version(collprovider, collcollate);
+
 	newoid = CollationCreate(collName,
 							 collNamespace,
 							 GetUserId(),
@@ -217,6 +227,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collencoding,
 							 collcollate,
 							 collctype,
+							 collversion,
 							 if_not_exists,
 							 false);	/* not quiet */
 
@@ -267,13 +278,101 @@ IsThereCollationInNamespace(const char *collname, Oid nspOid)
 						collname, get_namespace_name(nspOid))));
 }
 
+/*
+ * ALTER COLLATION
+ */
+ObjectAddress
+AlterCollation(AlterCollationStmt *stmt)
+{
+	Relation	rel;
+	Oid			collOid;
+	HeapTuple	tup;
+	Form_pg_collation collForm;
+	Datum		collversion;
+	bool		isnull;
+	char	   *oldversion;
+	char	   *newversion;
+	ObjectAddress address;
+
+	rel = table_open(CollationRelationId, RowExclusiveLock);
+	collOid = get_collation_oid(stmt->collname, false);
+
+	if (!pg_collation_ownercheck(collOid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_COLLATION,
+					   NameListToString(stmt->collname));
+
+	tup = SearchSysCacheCopy1(COLLOID, ObjectIdGetDatum(collOid));
+	if (!HeapTupleIsValid(tup))
+		elog(ERROR, "cache lookup failed for collation %u", collOid);
+
+	collForm = (Form_pg_collation) GETSTRUCT(tup);
+	collversion = SysCacheGetAttr(COLLOID, tup, Anum_pg_collation_collversion,
+								  &isnull);
+	oldversion = isnull ? NULL : TextDatumGetCString(collversion);
+
+	newversion = get_collation_actual_version(collForm->collprovider, NameStr(collForm->collcollate));
+
+	/* cannot change from NULL to non-NULL or vice versa */
+	if ((!oldversion && newversion) || (oldversion && !newversion))
+		elog(ERROR, "invalid collation version change");
+	else if (oldversion && newversion && strcmp(newversion, oldversion) != 0)
+	{
+		bool		nulls[Natts_pg_collation];
+		bool		replaces[Natts_pg_collation];
+		Datum		values[Natts_pg_collation];
+
+		ereport(NOTICE,
+				(errmsg("changing version from %s to %s",
+						oldversion, newversion)));
+
+		memset(values, 0, sizeof(values));
+		memset(nulls, false, sizeof(nulls));
+		memset(replaces, false, sizeof(replaces));
+
+		values[Anum_pg_collation_collversion - 1] = CStringGetTextDatum(newversion);
+		replaces[Anum_pg_collation_collversion - 1] = true;
+
+		tup = heap_modify_tuple(tup, RelationGetDescr(rel),
+								values, nulls, replaces);
+	}
+	else
+		ereport(NOTICE,
+				(errmsg("version has not changed")));
+
+	CatalogTupleUpdate(rel, &tup->t_self, tup);
+
+	InvokeObjectPostAlterHook(CollationRelationId, collOid, 0);
+
+	ObjectAddressSet(address, CollationRelationId, collOid);
+
+	heap_freetuple(tup);
+	table_close(rel, NoLock);
+
+	return address;
+}
+
+
 Datum
 pg_collation_actual_version(PG_FUNCTION_ARGS)
 {
 	Oid			collid = PG_GETARG_OID(0);
+	HeapTuple	tp;
+	char	   *collcollate;
+	char		collprovider;
 	char	   *version;
 
-	version = get_collation_version_for_oid(collid, true);
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
+	if (!HeapTupleIsValid(tp))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("collation with OID %u does not exist", collid)));
+
+	collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
+	collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+
+	ReleaseSysCache(tp);
+
+	version = get_collation_actual_version(collprovider, collcollate);
 
 	if (version)
 		PG_RETURN_TEXT_P(cstring_to_text(version));
@@ -495,6 +594,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
 									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
+									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
 			if (OidIsValid(collid))
 			{
@@ -555,6 +655,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			collid = CollationCreate(alias, nspid, GetUserId(),
 									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
+									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
 			if (OidIsValid(collid))
 			{
@@ -616,6 +717,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 									 nspid, GetUserId(),
 									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
+									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
 			if (OidIsValid(collid))
 			{
diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index df4768952d5..acae19176c0 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -555,7 +555,7 @@ CreateStatistics(CreateStatsStmt *stmt)
 										(Node *) stxexprs,
 										relid,
 										DEPENDENCY_NORMAL,
-										DEPENDENCY_AUTO, false, true);
+										DEPENDENCY_AUTO, false);
 
 	/*
 	 * Also add dependencies on namespace and owner.  These are required
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 0da61784d7a..3b5d4116839 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -94,7 +94,6 @@
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/partcache.h"
-#include "utils/pg_locale.h"
 #include "utils/relcache.h"
 #include "utils/ruleutils.h"
 #include "utils/snapmgr.h"
@@ -602,7 +601,6 @@ static void refuseDupeIndexAttach(Relation parentIdx, Relation partIdx,
 								  Relation partitionTbl);
 static List *GetParentedForeignKeyRefs(Relation partition);
 static void ATDetachCheckNoForeignKeyRefs(Relation partition);
-static void ATExecAlterCollationRefreshVersion(Relation rel, List *coll);
 static char GetAttributeCompression(Form_pg_attribute att, char *compression);
 
 
@@ -4333,10 +4331,6 @@ AlterTableGetLockLevel(List *cmds)
 				cmd_lockmode = AccessShareLock;
 				break;
 
-			case AT_AlterCollationRefreshVersion:
-				cmd_lockmode = AccessExclusiveLock;
-				break;
-
 			default:			/* oops */
 				elog(ERROR, "unrecognized alter table type: %d",
 					 (int) cmd->subtype);
@@ -4524,12 +4518,6 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* This command never recurses */
 			pass = AT_PASS_MISC;
 			break;
-		case AT_AlterCollationRefreshVersion:	/* ALTER COLLATION ... REFRESH
-												 * VERSION */
-			ATSimplePermissions(rel, ATT_INDEX);
-			/* This command never recurses */
-			pass = AT_PASS_MISC;
-			break;
 		case AT_SetStorage:		/* ALTER COLUMN SET STORAGE */
 			ATSimplePermissions(rel, ATT_TABLE | ATT_MATVIEW | ATT_FOREIGN_TABLE);
 			ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode, context);
@@ -5139,11 +5127,6 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		case AT_DetachPartitionFinalize:
 			ATExecDetachPartitionFinalize(rel, ((PartitionCmd *) cmd->def)->name);
 			break;
-		case AT_AlterCollationRefreshVersion:
-			/* ATPrepCmd ensured it must be an index */
-			Assert(rel->rd_rel->relkind == RELKIND_INDEX);
-			ATExecAlterCollationRefreshVersion(rel, cmd->object);
-			break;
 		default:				/* oops */
 			elog(ERROR, "unrecognized alter table type: %d",
 				 (int) cmd->subtype);
@@ -18627,20 +18610,6 @@ ATDetachCheckNoForeignKeyRefs(Relation partition)
 }
 
 /*
- * ALTER INDEX ... ALTER COLLATION ... REFRESH VERSION
- *
- * Update refobjversion to the current collation version by force.  This clears
- * warnings about version mismatches without the need to run REINDEX,
- * potentially hiding corruption due to ordering changes.
- */
-static void
-ATExecAlterCollationRefreshVersion(Relation rel, List *coll)
-{
-	index_update_collation_versions(rel->rd_id, get_collation_oid(coll, false));
-	CacheInvalidateRelcache(rel);
-}
-
-/*
  * resolve column compression specification to compression method.
  */
 static char
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 632cc31a045..f5a7760740f 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -3347,7 +3347,6 @@ _copyAlterTableCmd(const AlterTableCmd *from)
 
 	COPY_SCALAR_FIELD(subtype);
 	COPY_STRING_FIELD(name);
-	COPY_NODE_FIELD(object);
 	COPY_SCALAR_FIELD(num);
 	COPY_NODE_FIELD(newowner);
 	COPY_NODE_FIELD(def);
@@ -3357,6 +3356,16 @@ _copyAlterTableCmd(const AlterTableCmd *from)
 	return newnode;
 }
 
+static AlterCollationStmt *
+_copyAlterCollationStmt(const AlterCollationStmt *from)
+{
+	AlterCollationStmt *newnode = makeNode(AlterCollationStmt);
+
+	COPY_NODE_FIELD(collname);
+
+	return newnode;
+}
+
 static AlterDomainStmt *
 _copyAlterDomainStmt(const AlterDomainStmt *from)
 {
@@ -5369,6 +5378,9 @@ copyObjectImpl(const void *from)
 		case T_AlterTableCmd:
 			retval = _copyAlterTableCmd(from);
 			break;
+		case T_AlterCollationStmt:
+			retval = _copyAlterCollationStmt(from);
+			break;
 		case T_AlterDomainStmt:
 			retval = _copyAlterDomainStmt(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index a410a29a178..ce76d093dda 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1141,6 +1141,14 @@ _equalAlterTableCmd(const AlterTableCmd *a, const AlterTableCmd *b)
 }
 
 static bool
+_equalAlterCollationStmt(const AlterCollationStmt *a, const AlterCollationStmt *b)
+{
+	COMPARE_NODE_FIELD(collname);
+
+	return true;
+}
+
+static bool
 _equalAlterDomainStmt(const AlterDomainStmt *a, const AlterDomainStmt *b)
 {
 	COMPARE_SCALAR_FIELD(subtype);
@@ -3362,6 +3370,9 @@ equal(const void *a, const void *b)
 		case T_AlterTableCmd:
 			retval = _equalAlterTableCmd(a, b);
 			break;
+		case T_AlterCollationStmt:
+			retval = _equalAlterCollationStmt(a, b);
+			break;
 		case T_AlterDomainStmt:
 			retval = _equalAlterDomainStmt(a, b);
 			break;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 295ce114506..c5194fdbbf2 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -27,7 +27,6 @@
 #include "access/xlog.h"
 #include "catalog/catalog.h"
 #include "catalog/heap.h"
-#include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_statistic_ext.h"
@@ -199,14 +198,6 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 			indexRelation = index_open(indexoid, lmode);
 			index = indexRelation->rd_index;
 
-			/* Warn if any dependent collations' versions have moved. */
-			if (!IsSystemRelation(relation) &&
-				!indexRelation->rd_version_checked)
-			{
-				index_check_collation_versions(indexoid);
-				indexRelation->rd_version_checked = true;
-			}
-
 			/*
 			 * Ignore invalid indexes, since they can't safely be used for
 			 * queries.  Note that this is OK because the data structure we
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index b4ab4014c87..aaf1a51f685 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -263,7 +263,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 }
 
 %type <node>	stmt toplevel_stmt schema_stmt routine_body_stmt
-		AlterEventTrigStmt
+		AlterEventTrigStmt AlterCollationStmt
 		AlterDatabaseStmt AlterDatabaseSetStmt AlterDomainStmt AlterEnumStmt
 		AlterFdwStmt AlterForeignServerStmt AlterGroupStmt
 		AlterObjectDependsStmt AlterObjectSchemaStmt AlterOwnerStmt
@@ -902,6 +902,7 @@ toplevel_stmt:
 
 stmt:
 			AlterEventTrigStmt
+			| AlterCollationStmt
 			| AlterDatabaseStmt
 			| AlterDatabaseSetStmt
 			| AlterDefaultPrivilegesStmt
@@ -2682,14 +2683,6 @@ alter_table_cmd:
 					n->subtype = AT_NoForceRowSecurity;
 					$$ = (Node *)n;
 				}
-			/* ALTER INDEX <name> ALTER COLLATION ... REFRESH VERSION */
-			| ALTER COLLATION any_name REFRESH VERSION_P
-				{
-					AlterTableCmd *n = makeNode(AlterTableCmd);
-					n->subtype = AT_AlterCollationRefreshVersion;
-					n->object = $3;
-					$$ = (Node *)n;
-				}
 			| alter_generic_options
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
@@ -10379,6 +10372,21 @@ drop_option:
 
 /*****************************************************************************
  *
+ *		ALTER COLLATION
+ *
+ *****************************************************************************/
+
+AlterCollationStmt: ALTER COLLATION any_name REFRESH VERSION_P
+				{
+					AlterCollationStmt *n = makeNode(AlterCollationStmt);
+					n->collname = $3;
+					$$ = (Node *)n;
+				}
+		;
+
+
+/*****************************************************************************
+ *
  *		ALTER SYSTEM
  *
  * This is used to change configuration parameters persistently.
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 16c6f17e235..1a8fc167733 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -1850,6 +1850,10 @@ ProcessUtilitySlow(ParseState *pstate,
 				address = AlterStatistics((AlterStatsStmt *) parsetree);
 				break;
 
+			case T_AlterCollationStmt:
+				address = AlterCollation((AlterCollationStmt *) parsetree);
+				break;
+
 			default:
 				elog(ERROR, "unrecognized node type: %d",
 					 (int) nodeTag(parsetree));
@@ -3001,6 +3005,10 @@ CreateCommandTag(Node *parsetree)
 			tag = CMDTAG_DROP_SUBSCRIPTION;
 			break;
 
+		case T_AlterCollationStmt:
+			tag = CMDTAG_ALTER_COLLATION;
+			break;
+
 		case T_PrepareStmt:
 			tag = CMDTAG_PREPARE;
 			break;
@@ -3617,6 +3625,10 @@ GetCommandLogLevel(Node *parsetree)
 			lev = LOGSTMT_DDL;
 			break;
 
+		case T_AlterCollationStmt:
+			lev = LOGSTMT_DDL;
+			break;
+
 			/* already-planned queries */
 		case T_PlannedStmt:
 			{
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index aa4874163f8..eab089f252f 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -57,9 +57,7 @@
 #include "access/htup_details.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_control.h"
-#include "catalog/pg_database.h"
 #include "mb/pg_wchar.h"
-#include "miscadmin.h"
 #include "utils/builtins.h"
 #include "utils/formatting.h"
 #include "utils/hsearch.h"
@@ -127,9 +125,6 @@ static char *IsoLocaleName(const char *);	/* MSVC specific */
 static void icu_set_collation_attributes(UCollator *collator, const char *loc);
 #endif
 
-static char *get_collation_actual_version(char collprovider,
-										  const char *collcollate);
-
 /*
  * pg_perm_setlocale
  *
@@ -1488,10 +1483,12 @@ pg_newlocale_from_collation(Oid collid)
 		/* We haven't computed this yet in this session, so do it */
 		HeapTuple	tp;
 		Form_pg_collation collform;
-		const char *collcollate pg_attribute_unused();
+		const char *collcollate;
 		const char *collctype pg_attribute_unused();
 		struct pg_locale_struct result;
 		pg_locale_t resultp;
+		Datum		collversion;
+		bool		isnull;
 
 		tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
 		if (!HeapTupleIsValid(tp))
@@ -1593,6 +1590,41 @@ pg_newlocale_from_collation(Oid collid)
 #endif							/* not USE_ICU */
 		}
 
+		collversion = SysCacheGetAttr(COLLOID, tp, Anum_pg_collation_collversion,
+									  &isnull);
+		if (!isnull)
+		{
+			char	   *actual_versionstr;
+			char	   *collversionstr;
+
+			actual_versionstr = get_collation_actual_version(collform->collprovider, collcollate);
+			if (!actual_versionstr)
+			{
+				/*
+				 * This could happen when specifying a version in CREATE
+				 * COLLATION for a libc locale, or manually creating a mess in
+				 * the catalogs.
+				 */
+				ereport(ERROR,
+						(errmsg("collation \"%s\" has no actual version, but a version was specified",
+								NameStr(collform->collname))));
+			}
+			collversionstr = TextDatumGetCString(collversion);
+
+			if (strcmp(actual_versionstr, collversionstr) != 0)
+				ereport(WARNING,
+						(errmsg("collation \"%s\" has version mismatch",
+								NameStr(collform->collname)),
+						 errdetail("The collation in the database was created using version %s, "
+								   "but the operating system provides version %s.",
+								   collversionstr, actual_versionstr),
+						 errhint("Rebuild all objects affected by this collation and run "
+								 "ALTER COLLATION %s REFRESH VERSION, "
+								 "or build PostgreSQL with the right library version.",
+								 quote_qualified_identifier(get_namespace_name(collform->collnamespace),
+															NameStr(collform->collname)))));
+		}
+
 		ReleaseSysCache(tp);
 
 		/* We'll keep the pg_locale_t structures in TopMemoryContext */
@@ -1609,7 +1641,7 @@ pg_newlocale_from_collation(Oid collid)
  * Get provider-specific collation version string for the given collation from
  * the operating system/library.
  */
-static char *
+char *
 get_collation_actual_version(char collprovider, const char *collcollate)
 {
 	char	   *collversion = NULL;
@@ -1697,49 +1729,6 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 	return collversion;
 }
 
-/*
- * Get provider-specific collation version string for a given collation OID.
- * Return NULL if the provider doesn't support versions, or the collation is
- * unversioned (for example "C").  Unknown OIDs result in NULL if missing_ok is
- * true.
- */
-char *
-get_collation_version_for_oid(Oid oid, bool missing_ok)
-{
-	HeapTuple	tp;
-	char	   *version;
-
-	if (oid == DEFAULT_COLLATION_OID)
-	{
-		Form_pg_database dbform;
-
-		tp = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
-		if (!HeapTupleIsValid(tp))
-			elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
-		dbform = (Form_pg_database) GETSTRUCT(tp);
-		version = get_collation_actual_version(COLLPROVIDER_LIBC,
-											   NameStr(dbform->datcollate));
-	}
-	else
-	{
-		Form_pg_collation collform;
-
-		tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(oid));
-		if (!HeapTupleIsValid(tp))
-		{
-			if (missing_ok)
-				return NULL;
-			elog(ERROR, "cache lookup failed for collation %u", oid);
-		}
-		collform = (Form_pg_collation) GETSTRUCT(tp);
-		version = get_collation_actual_version(collform->collprovider,
-											   NameStr(collform->collcollate));
-	}
-
-	ReleaseSysCache(tp);
-
-	return version;
-}
 
 #ifdef USE_ICU
 /*
diff --git a/src/backend/utils/adt/pg_upgrade_support.c b/src/backend/utils/adt/pg_upgrade_support.c
index a575c950790..b5b46d72312 100644
--- a/src/backend/utils/adt/pg_upgrade_support.c
+++ b/src/backend/utils/adt/pg_upgrade_support.c
@@ -13,7 +13,6 @@
 
 #include "catalog/binary_upgrade.h"
 #include "catalog/heap.h"
-#include "catalog/index.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_type.h"
 #include "commands/extension.h"
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 31c8e07f2a7..bd88f6105ba 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -42,7 +42,6 @@
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/catalog.h"
-#include "catalog/index.h"
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
 #include "catalog/partition.h"
@@ -6069,7 +6068,6 @@ load_relcache_init_file(bool shared)
 		rel->rd_idattr = NULL;
 		rel->rd_pubactions = NULL;
 		rel->rd_statvalid = false;
-		rel->rd_version_checked = false;
 		rel->rd_statlist = NIL;
 		rel->rd_fkeyvalid = false;
 		rel->rd_fkeylist = NIL;
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 3bc86635f79..fc054af5ba1 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -180,7 +180,6 @@ typedef struct _dumpOptions
 
 	int			sequence_data;	/* dump sequence data even in schema-only mode */
 	int			do_nothing;
-	int			coll_unknown;
 } DumpOptions;
 
 /*
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 3cb3598f2b5..e384690d94a 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -46,7 +46,6 @@
 #include "catalog/pg_attribute_d.h"
 #include "catalog/pg_cast_d.h"
 #include "catalog/pg_class_d.h"
-#include "catalog/pg_collation_d.h"
 #include "catalog/pg_default_acl_d.h"
 #include "catalog/pg_largeobject_d.h"
 #include "catalog/pg_largeobject_metadata_d.h"
@@ -296,9 +295,6 @@ static void binary_upgrade_extension_member(PQExpBuffer upgrade_buffer,
 static const char *getAttrName(int attrnum, const TableInfo *tblInfo);
 static const char *fmtCopyColumnList(const TableInfo *ti, PQExpBuffer buffer);
 static bool nonemptyReloptions(const char *reloptions);
-static void appendIndexCollationVersion(PQExpBuffer buffer, const IndxInfo *indxinfo,
-										bool coll_unknown,
-										Archive *fout);
 static void appendReloptionsArrayAH(PQExpBuffer buffer, const char *reloptions,
 									const char *prefix, Archive *fout);
 static char *get_synchronized_snapshot(Archive *fout);
@@ -401,7 +397,6 @@ main(int argc, char **argv)
 		{"on-conflict-do-nothing", no_argument, &dopt.do_nothing, 1},
 		{"rows-per-insert", required_argument, NULL, 10},
 		{"include-foreign-data", required_argument, NULL, 11},
-		{"index-collation-versions-unknown", no_argument, &dopt.coll_unknown, 1},
 
 		{NULL, 0, NULL, 0}
 	};
@@ -734,10 +729,6 @@ main(int argc, char **argv)
 	if (archiveFormat != archDirectory && numWorkers > 1)
 		fatal("parallel backup only supported by the directory format");
 
-	/* Unknown collation versions only relevant in binary upgrade mode */
-	if (dopt.coll_unknown && !dopt.binary_upgrade)
-		fatal("option --index-collation-versions-unknown only works in binary upgrade mode");
-
 	/* Open the output file */
 	fout = CreateArchive(filename, archiveFormat, compressLevel, dosync,
 						 archiveMode, setupDumpWorker);
@@ -7227,9 +7218,7 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 				i_tablespace,
 				i_indreloptions,
 				i_indstatcols,
-				i_indstatvals,
-				i_inddependcollnames,
-				i_inddependcollversions;
+				i_indstatvals;
 	int			ntups;
 
 	for (i = 0; i < numTables; i++)
@@ -7265,64 +7254,7 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 		 * is not.
 		 */
 		resetPQExpBuffer(query);
-		if (fout->remoteVersion >= 140000)
-		{
-			appendPQExpBuffer(query,
-							  "SELECT t.tableoid, t.oid, "
-							  "t.relname AS indexname, "
-							  "inh.inhparent AS parentidx, "
-							  "pg_catalog.pg_get_indexdef(i.indexrelid) AS indexdef, "
-							  "i.indnkeyatts AS indnkeyatts, "
-							  "i.indnatts AS indnatts, "
-							  "i.indkey, i.indisclustered, "
-							  "i.indisreplident, "
-							  "c.contype, c.conname, "
-							  "c.condeferrable, c.condeferred, "
-							  "c.tableoid AS contableoid, "
-							  "c.oid AS conoid, "
-							  "pg_catalog.pg_get_constraintdef(c.oid, false) AS condef, "
-							  "(SELECT spcname FROM pg_catalog.pg_tablespace s WHERE s.oid = t.reltablespace) AS tablespace, "
-							  "t.reloptions AS indreloptions, "
-							  "(SELECT pg_catalog.array_agg(attnum ORDER BY attnum) "
-							  "  FROM pg_catalog.pg_attribute "
-							  "  WHERE attrelid = i.indexrelid AND "
-							  "    attstattarget >= 0) AS indstatcols,"
-							  "(SELECT pg_catalog.array_agg(attstattarget ORDER BY attnum) "
-							  "  FROM pg_catalog.pg_attribute "
-							  "  WHERE attrelid = i.indexrelid AND "
-							  "    attstattarget >= 0) AS indstatvals, "
-							  "(SELECT pg_catalog.array_agg(quote_ident(ns.nspname) || '.' || quote_ident(c.collname) ORDER BY refobjid) "
-							  "  FROM pg_catalog.pg_depend d "
-							  "  JOIN pg_catalog.pg_collation c ON (c.oid = d.refobjid) "
-							  "  JOIN pg_catalog.pg_namespace ns ON (c.collnamespace = ns.oid) "
-							  "  WHERE d.classid = 'pg_catalog.pg_class'::regclass AND "
-							  "    d.objid = i.indexrelid AND "
-							  "    d.objsubid = 0 AND "
-							  "    d.refclassid = 'pg_catalog.pg_collation'::regclass AND "
-							  "    d.refobjversion IS NOT NULL) AS inddependcollnames, "
-							  "(SELECT pg_catalog.array_agg(quote_literal(refobjversion) ORDER BY refobjid) "
-							  "  FROM pg_catalog.pg_depend "
-							  "  WHERE classid = 'pg_catalog.pg_class'::regclass AND "
-							  "    objid = i.indexrelid AND "
-							  "    objsubid = 0 AND "
-							  "    refclassid = 'pg_catalog.pg_collation'::regclass AND "
-							  "    refobjversion IS NOT NULL) AS inddependcollversions "
-							  "FROM pg_catalog.pg_index i "
-							  "JOIN pg_catalog.pg_class t ON (t.oid = i.indexrelid) "
-							  "JOIN pg_catalog.pg_class t2 ON (t2.oid = i.indrelid) "
-							  "LEFT JOIN pg_catalog.pg_constraint c "
-							  "ON (i.indrelid = c.conrelid AND "
-							  "i.indexrelid = c.conindid AND "
-							  "c.contype IN ('p','u','x')) "
-							  "LEFT JOIN pg_catalog.pg_inherits inh "
-							  "ON (inh.inhrelid = indexrelid) "
-							  "WHERE i.indrelid = '%u'::pg_catalog.oid "
-							  "AND (i.indisvalid OR t2.relkind = 'p') "
-							  "AND i.indisready "
-							  "ORDER BY indexname",
-							  tbinfo->dobj.catId.oid);
-		}
-		else if (fout->remoteVersion >= 110000)
+		if (fout->remoteVersion >= 110000)
 		{
 			appendPQExpBuffer(query,
 							  "SELECT t.tableoid, t.oid, "
@@ -7347,9 +7279,7 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 							  "(SELECT pg_catalog.array_agg(attstattarget ORDER BY attnum) "
 							  "  FROM pg_catalog.pg_attribute "
 							  "  WHERE attrelid = i.indexrelid AND "
-							  "    attstattarget >= 0) AS indstatvals, "
-							  "'{}' AS inddependcollnames, "
-							  "'{}' AS inddependcollversions "
+							  "    attstattarget >= 0) AS indstatvals "
 							  "FROM pg_catalog.pg_index i "
 							  "JOIN pg_catalog.pg_class t ON (t.oid = i.indexrelid) "
 							  "JOIN pg_catalog.pg_class t2 ON (t2.oid = i.indrelid) "
@@ -7388,9 +7318,7 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 							  "(SELECT spcname FROM pg_catalog.pg_tablespace s WHERE s.oid = t.reltablespace) AS tablespace, "
 							  "t.reloptions AS indreloptions, "
 							  "'' AS indstatcols, "
-							  "'' AS indstatvals, "
-							  "'{}' AS inddependcollnames, "
-							  "'{}' AS inddependcollversions "
+							  "'' AS indstatvals "
 							  "FROM pg_catalog.pg_index i "
 							  "JOIN pg_catalog.pg_class t ON (t.oid = i.indexrelid) "
 							  "LEFT JOIN pg_catalog.pg_constraint c "
@@ -7425,9 +7353,7 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 							  "(SELECT spcname FROM pg_catalog.pg_tablespace s WHERE s.oid = t.reltablespace) AS tablespace, "
 							  "t.reloptions AS indreloptions, "
 							  "'' AS indstatcols, "
-							  "'' AS indstatvals, "
-							  "'{}' AS inddependcollnames, "
-							  "'{}' AS inddependcollversions "
+							  "'' AS indstatvals "
 							  "FROM pg_catalog.pg_index i "
 							  "JOIN pg_catalog.pg_class t ON (t.oid = i.indexrelid) "
 							  "LEFT JOIN pg_catalog.pg_constraint c "
@@ -7458,9 +7384,7 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 							  "(SELECT spcname FROM pg_catalog.pg_tablespace s WHERE s.oid = t.reltablespace) AS tablespace, "
 							  "t.reloptions AS indreloptions, "
 							  "'' AS indstatcols, "
-							  "'' AS indstatvals, "
-							  "'{}' AS inddependcollnames, "
-							  "'{}' AS inddependcollversions "
+							  "'' AS indstatvals "
 							  "FROM pg_catalog.pg_index i "
 							  "JOIN pg_catalog.pg_class t ON (t.oid = i.indexrelid) "
 							  "LEFT JOIN pg_catalog.pg_depend d "
@@ -7494,9 +7418,7 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 							  "(SELECT spcname FROM pg_catalog.pg_tablespace s WHERE s.oid = t.reltablespace) AS tablespace, "
 							  "null AS indreloptions, "
 							  "'' AS indstatcols, "
-							  "'' AS indstatvals, "
-							  "'{}' AS inddependcollnames, "
-							  "'{}' AS inddependcollversions "
+							  "'' AS indstatvals "
 							  "FROM pg_catalog.pg_index i "
 							  "JOIN pg_catalog.pg_class t ON (t.oid = i.indexrelid) "
 							  "LEFT JOIN pg_catalog.pg_depend d "
@@ -7536,8 +7458,6 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 		i_indreloptions = PQfnumber(res, "indreloptions");
 		i_indstatcols = PQfnumber(res, "indstatcols");
 		i_indstatvals = PQfnumber(res, "indstatvals");
-		i_inddependcollnames = PQfnumber(res, "inddependcollnames");
-		i_inddependcollversions = PQfnumber(res, "inddependcollversions");
 
 		tbinfo->indexes = indxinfo =
 			(IndxInfo *) pg_malloc(ntups * sizeof(IndxInfo));
@@ -7563,8 +7483,6 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables)
 			indxinfo[j].indreloptions = pg_strdup(PQgetvalue(res, j, i_indreloptions));
 			indxinfo[j].indstatcols = pg_strdup(PQgetvalue(res, j, i_indstatcols));
 			indxinfo[j].indstatvals = pg_strdup(PQgetvalue(res, j, i_indstatvals));
-			indxinfo[j].inddependcollnames = pg_strdup(PQgetvalue(res, j, i_inddependcollnames));
-			indxinfo[j].inddependcollversions = pg_strdup(PQgetvalue(res, j, i_inddependcollversions));
 			indxinfo[j].indkeys = (Oid *) pg_malloc(indxinfo[j].indnattrs * sizeof(Oid));
 			parseOidArray(PQgetvalue(res, j, i_indkey),
 						  indxinfo[j].indkeys, indxinfo[j].indnattrs);
@@ -13933,10 +13851,12 @@ dumpCollation(Archive *fout, const CollInfo *collinfo)
 
 	if (fout->remoteVersion >= 100000)
 		appendPQExpBufferStr(query,
-							 "collprovider, ");
+							 "collprovider, "
+							 "collversion, ");
 	else
 		appendPQExpBufferStr(query,
-							 "'c' AS collprovider, ");
+							 "'c' AS collprovider, "
+							 "NULL AS collversion, ");
 
 	if (fout->remoteVersion >= 120000)
 		appendPQExpBufferStr(query,
@@ -13997,6 +13917,24 @@ dumpCollation(Archive *fout, const CollInfo *collinfo)
 		appendStringLiteralAH(q, collctype, fout);
 	}
 
+	/*
+	 * For binary upgrade, carry over the collation version.  For normal
+	 * dump/restore, omit the version, so that it is computed upon restore.
+	 */
+	if (dopt->binary_upgrade)
+	{
+		int			i_collversion;
+
+		i_collversion = PQfnumber(res, "collversion");
+		if (!PQgetisnull(res, 0, i_collversion))
+		{
+			appendPQExpBufferStr(q, ", version = ");
+			appendStringLiteralAH(q,
+								  PQgetvalue(res, 0, i_collversion),
+								  fout);
+		}
+	}
+
 	appendPQExpBufferStr(q, ");\n");
 
 	if (dopt->binary_upgrade)
@@ -16770,8 +16708,7 @@ dumpIndex(Archive *fout, const IndxInfo *indxinfo)
 
 	/*
 	 * If there's an associated constraint, don't dump the index per se, but
-	 * do dump any comment, or in binary upgrade mode dependency on a
-	 * collation version for it.  (This is safe because dependency ordering
+	 * do dump any comment for it.  (This is safe because dependency ordering
 	 * will have ensured the constraint is emitted first.)	Note that the
 	 * emitted comment has to be shown as depending on the constraint, not the
 	 * index, in such cases.
@@ -16843,9 +16780,6 @@ dumpIndex(Archive *fout, const IndxInfo *indxinfo)
 									"pg_catalog.pg_class",
 									"INDEX", qqindxname);
 
-		if (dopt->binary_upgrade)
-			appendIndexCollationVersion(q, indxinfo, dopt->coll_unknown, fout);
-
 		/* If the index defines identity, we need to record that. */
 		if (indxinfo->indisreplident)
 		{
@@ -16874,20 +16808,6 @@ dumpIndex(Archive *fout, const IndxInfo *indxinfo)
 		if (indstatvalsarray)
 			free(indstatvalsarray);
 	}
-	else if (dopt->binary_upgrade)
-	{
-		appendIndexCollationVersion(q, indxinfo, dopt->coll_unknown, fout);
-
-		if (indxinfo->dobj.dump & DUMP_COMPONENT_DEFINITION)
-			ArchiveEntry(fout, indxinfo->dobj.catId, indxinfo->dobj.dumpId,
-						 ARCHIVE_OPTS(.tag = indxinfo->dobj.name,
-									  .namespace = tbinfo->dobj.namespace->dobj.name,
-									  .tablespace = indxinfo->tablespace,
-									  .owner = tbinfo->rolname,
-									  .description = "INDEX",
-									  .section = SECTION_POST_DATA,
-									  .createStmt = q->data));
-	}
 
 	/* Dump Index Comments */
 	if (indxinfo->dobj.dump & DUMP_COMPONENT_COMMENT)
@@ -18897,82 +18817,6 @@ nonemptyReloptions(const char *reloptions)
 }
 
 /*
- * Generate UPDATE statements to import the collation versions into the new
- * cluster, during a binary upgrade.
- */
-static void
-appendIndexCollationVersion(PQExpBuffer buffer, const IndxInfo *indxinfo,
-							bool coll_unknown, Archive *fout)
-{
-	char	   *inddependcollnames = indxinfo->inddependcollnames;
-	char	   *inddependcollversions = indxinfo->inddependcollversions;
-	char	  **inddependcollnamesarray;
-	char	  **inddependcollversionsarray;
-	int			ninddependcollnames;
-	int			ninddependcollversions;
-
-	/*
-	 * By default, the new cluster's index will have pg_depends rows with
-	 * current collation versions, meaning that we assume the index isn't
-	 * corrupted if importing from a release that didn't record versions.
-	 * However, if --index-collation-versions-unknown was passed in, then we
-	 * assume such indexes might be corrupted, and clobber versions with
-	 * 'unknown' to trigger version warnings.
-	 */
-	if (coll_unknown)
-	{
-		appendPQExpBuffer(buffer,
-						  "\n-- For binary upgrade, clobber new index's collation versions\n");
-		appendPQExpBuffer(buffer,
-						  "UPDATE pg_catalog.pg_depend SET refobjversion = 'unknown' WHERE objid = '%u'::pg_catalog.oid AND refclassid = 'pg_catalog.pg_collation'::regclass AND refobjversion IS NOT NULL;\n",
-						  indxinfo->dobj.catId.oid);
-	}
-
-	/* Restore the versions that were recorded by the old cluster (if any). */
-	if (strlen(inddependcollnames) == 0 && strlen(inddependcollversions) == 0)
-	{
-		ninddependcollnames = ninddependcollversions = 0;
-		inddependcollnamesarray = inddependcollversionsarray = NULL;
-	}
-	else
-	{
-		if (!parsePGArray(inddependcollnames,
-						  &inddependcollnamesarray,
-						  &ninddependcollnames))
-			fatal("could not parse index collation name array");
-		if (!parsePGArray(inddependcollversions,
-						  &inddependcollversionsarray,
-						  &ninddependcollversions))
-			fatal("could not parse index collation version array");
-	}
-
-	if (ninddependcollnames != ninddependcollversions)
-		fatal("mismatched number of collation names and versions for index");
-
-	if (ninddependcollnames > 0)
-		appendPQExpBufferStr(buffer,
-							 "\n-- For binary upgrade, restore old index's collation versions\n");
-	for (int i = 0; i < ninddependcollnames; i++)
-	{
-		/*
-		 * Import refobjversion from the old cluster, being careful to resolve
-		 * the collation OID by name in the new cluster.
-		 */
-		appendPQExpBuffer(buffer,
-						  "UPDATE pg_catalog.pg_depend SET refobjversion = %s WHERE objid = '%u'::pg_catalog.oid AND refclassid = 'pg_catalog.pg_collation'::regclass AND refobjversion IS NOT NULL AND refobjid = ",
-						  inddependcollversionsarray[i],
-						  indxinfo->dobj.catId.oid);
-		appendStringLiteralAH(buffer, inddependcollnamesarray[i], fout);
-		appendPQExpBuffer(buffer, "::regcollation;\n");
-	}
-
-	if (inddependcollnamesarray)
-		free(inddependcollnamesarray);
-	if (inddependcollversionsarray)
-		free(inddependcollversionsarray);
-}
-
-/*
  * Format a reloptions array and append it to the given buffer.
  *
  * "prefix" is prepended to the option names; typically it's "" or "toast.".
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index 53408430819..49e1b0a09c4 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -376,8 +376,6 @@ typedef struct _indxInfo
 	int			indnattrs;		/* total number of index attributes */
 	Oid		   *indkeys;		/* In spite of the name 'indkeys' this field
 								 * contains both key and nonkey attributes */
-	char	   *inddependcollnames; /* FQ names of depended-on collations */
-	char	   *inddependcollversions;	/* versions of the above */
 	bool		indisclustered;
 	bool		indisreplident;
 	Oid			parentidx;		/* if a partition, parent index OID */
diff --git a/src/bin/pg_upgrade/dump.c b/src/bin/pg_upgrade/dump.c
index 33d9591f374..90060d0f8eb 100644
--- a/src/bin/pg_upgrade/dump.c
+++ b/src/bin/pg_upgrade/dump.c
@@ -52,11 +52,9 @@ generate_old_dump(void)
 
 		parallel_exec_prog(log_file_name, NULL,
 						   "\"%s/pg_dump\" %s --schema-only --quote-all-identifiers "
-						   "--binary-upgrade --format=custom %s %s --file=\"%s\" %s",
+						   "--binary-upgrade --format=custom %s --file=\"%s\" %s",
 						   new_cluster.bindir, cluster_conn_opts(&old_cluster),
 						   log_opts.verbose ? "--verbose" : "",
-						   user_opts.ind_coll_unknown ?
-						   "--index-collation-versions-unknown" : "",
 						   sql_file_name, escaped_connstr.data);
 
 		termPQExpBuffer(&escaped_connstr);
diff --git a/src/bin/pg_upgrade/option.c b/src/bin/pg_upgrade/option.c
index 4b74f9eea7e..64bbda56508 100644
--- a/src/bin/pg_upgrade/option.c
+++ b/src/bin/pg_upgrade/option.c
@@ -56,7 +56,6 @@ parseCommandLine(int argc, char *argv[])
 		{"socketdir", required_argument, NULL, 's'},
 		{"verbose", no_argument, NULL, 'v'},
 		{"clone", no_argument, NULL, 1},
-		{"index-collation-versions-unknown", no_argument, NULL, 2},
 
 		{NULL, 0, NULL, 0}
 	};
@@ -204,10 +203,6 @@ parseCommandLine(int argc, char *argv[])
 				user_opts.transfer_mode = TRANSFER_MODE_CLONE;
 				break;
 
-			case 2:
-				user_opts.ind_coll_unknown = true;
-				break;
-
 			default:
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
 						os_info.progname);
@@ -312,8 +307,6 @@ usage(void)
 	printf(_("  -v, --verbose                 enable verbose internal logging\n"));
 	printf(_("  -V, --version                 display version information, then exit\n"));
 	printf(_("  --clone                       clone instead of copying files to new cluster\n"));
-	printf(_("  --index-collation-versions-unknown\n"
-			 "                                mark text indexes as needing to be rebuilt\n"));
 	printf(_("  -?, --help                    show this help, then exit\n"));
 	printf(_("\n"
 			 "Before running pg_upgrade you must:\n"
diff --git a/src/bin/pg_upgrade/pg_upgrade.h b/src/bin/pg_upgrade/pg_upgrade.h
index d7666da3f27..a5f71c5294f 100644
--- a/src/bin/pg_upgrade/pg_upgrade.h
+++ b/src/bin/pg_upgrade/pg_upgrade.h
@@ -292,7 +292,6 @@ typedef struct
 	transferMode transfer_mode; /* copy files or link them? */
 	int			jobs;			/* number of processes/threads to use */
 	char	   *socketdir;		/* directory to use for Unix sockets */
-	bool		ind_coll_unknown;	/* mark unknown index collation versions */
 } UserOpts;
 
 typedef struct
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 7c4933333b3..d917987fd58 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -45,7 +45,6 @@
 
 #include "catalog/pg_am_d.h"
 #include "catalog/pg_class_d.h"
-#include "catalog/pg_collation_d.h"
 #include "common.h"
 #include "libpq-fe.h"
 #include "pqexpbuffer.h"
@@ -842,20 +841,6 @@ static const SchemaQuery Query_for_list_of_collations = {
 "       (SELECT tgrelid FROM pg_catalog.pg_trigger "\
 "         WHERE pg_catalog.quote_ident(tgname)='%s')"
 
-/* the silly-looking length condition is just to eat up the current word */
-#define Query_for_list_of_colls_for_one_index \
-" SELECT DISTINCT pg_catalog.quote_ident(coll.collname) " \
-"   FROM pg_catalog.pg_depend d, pg_catalog.pg_collation coll, " \
-"     pg_catalog.pg_class c" \
-" WHERE (%d = pg_catalog.length('%s'))" \
-"   AND d.refclassid = " CppAsString2(CollationRelationId) \
-"   AND d.refobjid = coll.oid " \
-"   AND d.classid = " CppAsString2(RelationRelationId) \
-"   AND d.objid = c.oid " \
-"   AND c.relkind = " CppAsString2(RELKIND_INDEX) \
-"   AND pg_catalog.pg_table_is_visible(c.oid) " \
-"   AND c.relname = '%s'"
-
 #define Query_for_list_of_ts_configurations \
 "SELECT pg_catalog.quote_ident(cfgname) FROM pg_catalog.pg_ts_config "\
 " WHERE substring(pg_catalog.quote_ident(cfgname),1,%d)='%s'"
@@ -1769,15 +1754,14 @@ psql_completion(const char *text, int start, int end)
 	else if (Matches("ALTER", "INDEX", MatchAny))
 		COMPLETE_WITH("ALTER COLUMN", "OWNER TO", "RENAME TO", "SET",
 					  "RESET", "ATTACH PARTITION",
-					  "DEPENDS ON EXTENSION", "NO DEPENDS ON EXTENSION",
-					  "ALTER COLLATION");
+					  "DEPENDS ON EXTENSION", "NO DEPENDS ON EXTENSION");
 	else if (Matches("ALTER", "INDEX", MatchAny, "ATTACH"))
 		COMPLETE_WITH("PARTITION");
 	else if (Matches("ALTER", "INDEX", MatchAny, "ATTACH", "PARTITION"))
 		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_indexes, NULL);
 	/* ALTER INDEX <name> ALTER */
 	else if (Matches("ALTER", "INDEX", MatchAny, "ALTER"))
-		COMPLETE_WITH("COLLATION", "COLUMN");
+		COMPLETE_WITH("COLUMN");
 	/* ALTER INDEX <name> ALTER COLUMN */
 	else if (Matches("ALTER", "INDEX", MatchAny, "ALTER", "COLUMN"))
 	{
@@ -1816,15 +1800,10 @@ psql_completion(const char *text, int start, int end)
 					  "buffering =",	/* GiST */
 					  "pages_per_range =", "autosummarize ="	/* BRIN */
 			);
-	/* ALTER INDEX <name> ALTER COLLATION */
-	else if (Matches("ALTER", "INDEX", MatchAny, "ALTER", "COLLATION"))
-	{
-		completion_info_charp = prev3_wd;
-		COMPLETE_WITH_QUERY(Query_for_list_of_colls_for_one_index);
-	}
-	/* ALTER INDEX <name> ALTER COLLATION <name> */
-	else if (Matches("ALTER", "INDEX", MatchAny, "ALTER", "COLLATION", MatchAny))
-		COMPLETE_WITH("REFRESH VERSION");
+	else if (Matches("ALTER", "INDEX", MatchAny, "NO", "DEPENDS"))
+		COMPLETE_WITH("ON EXTENSION");
+	else if (Matches("ALTER", "INDEX", MatchAny, "DEPENDS"))
+		COMPLETE_WITH("ON EXTENSION");
 
 	/* ALTER LANGUAGE <name> */
 	else if (Matches("ALTER", "LANGUAGE", MatchAny))
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 22dcd0a270c..a54be88d7f1 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202104271
+#define CATALOG_VERSION_NO	202105051
 
 #endif
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index f272e2c99f8..fd44081e741 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -167,8 +167,7 @@ extern void recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 											Node *expr, Oid relId,
 											DependencyType behavior,
 											DependencyType self_behavior,
-											bool reverse_self,
-											bool record_version);
+											bool reverse_self);
 
 extern ObjectClass getObjectClass(const ObjectAddress *object);
 
@@ -188,30 +187,16 @@ extern void sort_object_addresses(ObjectAddresses *addrs);
 
 extern void free_object_addresses(ObjectAddresses *addrs);
 
-typedef bool(*VisitDependenciesOfCB) (const ObjectAddress *otherObject,
-									  const char *version,
-									  char **new_version,
-									  void *data);
-
-extern void visitDependenciesOf(const ObjectAddress *object,
-								VisitDependenciesOfCB callback,
-								void *data);
-
 /* in pg_depend.c */
 
 extern void recordDependencyOn(const ObjectAddress *depender,
 							   const ObjectAddress *referenced,
 							   DependencyType behavior);
 
-extern void recordDependencyOnCollations(ObjectAddress *myself,
-										 List *collations,
-										 bool record_version);
-
 extern void recordMultipleDependencies(const ObjectAddress *depender,
 									   const ObjectAddress *referenced,
 									   int nreferenced,
-									   DependencyType behavior,
-									   bool record_version);
+									   DependencyType behavior);
 
 extern void recordDependencyOnCurrentExtension(const ObjectAddress *object,
 											   bool isReplace);
@@ -232,6 +217,7 @@ extern long changeDependencyFor(Oid classId, Oid objectId,
 
 extern long changeDependenciesOf(Oid classId, Oid oldObjectId,
 								 Oid newObjectId);
+
 extern long changeDependenciesOn(Oid refClassId, Oid oldRefObjectId,
 								 Oid newRefObjectId);
 
diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index e22d506436b..008f723e104 100644
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -136,9 +136,6 @@ extern void FormIndexDatum(IndexInfo *indexInfo,
 						   Datum *values,
 						   bool *isnull);
 
-extern void index_check_collation_versions(Oid relid);
-extern void index_update_collation_versions(Oid relid, Oid coll);
-
 extern void index_build(Relation heapRelation,
 						Relation indexRelation,
 						IndexInfo *indexInfo,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index c6394ca2221..52bfd2cb7bf 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -41,6 +41,11 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
+#ifdef CATALOG_VARLEN			/* variable-length fields start here */
+	text		collversion BKI_DEFAULT(_null_);	/* provider-dependent */
+													/* version of */
+													/* collation data */
+#endif
 } FormData_pg_collation;
 
 /* ----------------
@@ -50,6 +55,8 @@ CATALOG(pg_collation,3456,CollationRelationId)
  */
 typedef FormData_pg_collation *Form_pg_collation;
 
+DECLARE_TOAST(pg_collation, 8888, 8889);
+
 DECLARE_UNIQUE_INDEX(pg_collation_name_enc_nsp_index, 3164, on pg_collation using btree(collname name_ops, collencoding int4_ops, collnamespace oid_ops));
 #define CollationNameEncNspIndexId 3164
 DECLARE_UNIQUE_INDEX_PKEY(pg_collation_oid_index, 3085, on pg_collation using btree(oid oid_ops));
@@ -70,6 +77,7 @@ extern Oid	CollationCreate(const char *collname, Oid collnamespace,
 							bool collisdeterministic,
 							int32 collencoding,
 							const char *collcollate, const char *collctype,
+							const char *collversion,
 							bool if_not_exists,
 							bool quiet);
 
diff --git a/src/include/catalog/pg_depend.h b/src/include/catalog/pg_depend.h
index 606a2a8e192..e0bc1141457 100644
--- a/src/include/catalog/pg_depend.h
+++ b/src/include/catalog/pg_depend.h
@@ -63,9 +63,6 @@ CATALOG(pg_depend,2608,DependRelationId)
 	 * field.  See DependencyType in catalog/dependency.h.
 	 */
 	char		deptype;		/* see codes in dependency.h */
-#ifdef CATALOG_VARLEN
-	text		refobjversion;	/* version of referenced object */
-#endif
 } FormData_pg_depend;
 
 /* ----------------
@@ -75,8 +72,6 @@ CATALOG(pg_depend,2608,DependRelationId)
  */
 typedef FormData_pg_depend *Form_pg_depend;
 
-DECLARE_TOAST(pg_depend, 8888, 8889);
-
 DECLARE_INDEX(pg_depend_depender_index, 2673, on pg_depend using btree(classid oid_ops, objid oid_ops, objsubid int4_ops));
 #define DependDependerIndexId  2673
 DECLARE_INDEX(pg_depend_reference_index, 2674, on pg_depend using btree(refclassid oid_ops, refobjid oid_ops, refobjsubid int4_ops));
diff --git a/src/include/catalog/pg_type.h b/src/include/catalog/pg_type.h
index 8ee5fa0507a..33557760e19 100644
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -390,8 +390,6 @@ extern void GenerateTypeDependencies(HeapTuple typeTuple,
 									 bool isDependentType,
 									 bool rebuild);
 
-extern List *GetTypeCollations(Oid typeObjectid);
-
 extern void RenameTypeInternal(Oid typeOid, const char *newTypeName,
 							   Oid typeNamespace);
 
diff --git a/src/include/commands/collationcmds.h b/src/include/commands/collationcmds.h
index 4e690458805..e49a5db0fbd 100644
--- a/src/include/commands/collationcmds.h
+++ b/src/include/commands/collationcmds.h
@@ -20,5 +20,6 @@
 
 extern ObjectAddress DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_exists);
 extern void IsThereCollationInNamespace(const char *collname, Oid nspOid);
+extern ObjectAddress AlterCollation(AlterCollationStmt *stmt);
 
 #endif							/* COLLATIONCMDS_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 615dfa26aa2..fea31232519 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1933,7 +1933,6 @@ typedef enum AlterTableType
 	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity,			/* DROP IDENTITY */
-	AT_AlterCollationRefreshVersion, /* ALTER COLLATION ... REFRESH VERSION */
 	AT_ReAddStatistics			/* internal to commands/tablecmds.c */
 } AlterTableType;
 
@@ -1950,7 +1949,6 @@ typedef struct AlterTableCmd	/* one subcommand of an ALTER TABLE */
 	AlterTableType subtype;		/* Type of table alteration to apply */
 	char	   *name;			/* column, constraint, or trigger to act on,
 								 * or tablespace */
-	List	   *object;			/* collation to act on if it's a collation */
 	int16		num;			/* attribute number for columns referenced by
 								 * number */
 	RoleSpec   *newowner;
@@ -1962,6 +1960,17 @@ typedef struct AlterTableCmd	/* one subcommand of an ALTER TABLE */
 
 
 /* ----------------------
+ * Alter Collation
+ * ----------------------
+ */
+typedef struct AlterCollationStmt
+{
+	NodeTag		type;
+	List	   *collname;
+} AlterCollationStmt;
+
+
+/* ----------------------
  *	Alter Domain
  *
  * The fields are used in different ways by the different variants of
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 5a37caefbe4..2946f46c76f 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -103,7 +103,7 @@ typedef struct pg_locale_struct *pg_locale_t;
 
 extern pg_locale_t pg_newlocale_from_collation(Oid collid);
 
-extern char *get_collation_version_for_oid(Oid collid, bool missing_ok);
+extern char *get_collation_actual_version(char collprovider, const char *collcollate);
 
 #ifdef USE_ICU
 extern int32_t icu_to_uchar(UChar **buff_uchar, const char *buff, size_t nbytes);
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 5bd44be9a79..774ac5b2b19 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -63,7 +63,6 @@ typedef struct RelationData
 	bool		rd_indexvalid;	/* is rd_indexlist valid? (also rd_pkindex and
 								 * rd_replidindex) */
 	bool		rd_statvalid;	/* is rd_statlist valid? */
-	bool		rd_version_checked; /* has version check been done yet? */
 
 	/*----------
 	 * rd_createSubid is the ID of the highest subtransaction the rel has
diff --git a/src/test/Makefile b/src/test/Makefile
index f7859c2fd5e..46275915ff3 100644
--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -12,8 +12,7 @@ subdir = src/test
 top_builddir = ../..
 include $(top_builddir)/src/Makefile.global
 
-SUBDIRS = perl regress isolation modules authentication recovery subscription \
-	  locale
+SUBDIRS = perl regress isolation modules authentication recovery subscription
 
 # Test suites that are not safe by default but can be run if selected
 # by the user via the whitespace-separated list in variable
diff --git a/src/test/locale/.gitignore b/src/test/locale/.gitignore
index 64e1bf2a803..620d3df4254 100644
--- a/src/test/locale/.gitignore
+++ b/src/test/locale/.gitignore
@@ -1,2 +1 @@
 /test-ctype
-/tmp_check/
diff --git a/src/test/locale/Makefile b/src/test/locale/Makefile
index 673e14dcd08..7ba096b5427 100644
--- a/src/test/locale/Makefile
+++ b/src/test/locale/Makefile
@@ -4,7 +4,6 @@ subdir = src/test/locale
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
-export with_icu
 
 PROGS = test-ctype
 DIRS = de_DE.ISO8859-1 gr_GR.ISO8859-7 koi8-r koi8-to-win1251
@@ -21,9 +20,3 @@ clean distclean maintainer-clean:
 # These behave like installcheck targets.
 check-%: all
 	@$(MAKE) -C `echo $@ | sed 's/^check-//'` test
-
-check:
-	$(prove_check)
-
-installcheck:
-	$(prove_installcheck)
diff --git a/src/test/locale/t/001_index.pl b/src/test/locale/t/001_index.pl
deleted file mode 100644
index a67f78cb719..00000000000
--- a/src/test/locale/t/001_index.pl
+++ /dev/null
@@ -1,67 +0,0 @@
-use strict;
-use warnings;
-
-use Config;
-use PostgresNode;
-use TestLib;
-use Test::More;
-
-if ($ENV{with_icu} eq 'yes')
-{
-	plan tests => 10;
-}
-else
-{
-	plan skip_all => 'ICU not supported by this build';
-}
-
-#### Set up the server
-
-note "setting up data directory";
-my $node = get_new_node('main');
-$node->init(extra => [ '--encoding=UTF8' ]);
-
-$ENV{PGHOST} = $node->host;
-$ENV{PGPORT} = $node->port;
-$node->start;
-
-sub test_index
-{
-	my ($err_like, $err_comm) = @_;
-	my ($ret, $out, $err) = $node->psql('postgres', "SELECT * FROM icu1");
-	is($ret, 0, 'SELECT should succeed.');
-	like($err, $err_like, $err_comm);
-}
-
-$node->safe_psql('postgres', 'CREATE TABLE icu1(val text);');
-$node->safe_psql('postgres', 'CREATE INDEX icu1_fr ON icu1 (val COLLATE "fr-x-icu");');
-
-test_index(qr/^$/, 'No warning should be raised');
-
-# Simulate different collation version
-$node->safe_psql('postgres',
-	"UPDATE pg_depend SET refobjversion = 'not_a_version'"
-	. " WHERE refobjversion IS NOT NULL"
-	. " AND objid::regclass::text = 'icu1_fr';");
-
-test_index(qr/index "icu1_fr" depends on collation "fr-x-icu" version "not_a_version", but the current version is/,
-	'Different collation version warning should be raised.');
-
-$node->safe_psql('postgres', 'ALTER INDEX icu1_fr ALTER COLLATION "fr-x-icu" REFRESH VERSION;');
-
-test_index(qr/^$/, 'No warning should be raised');
-
-# Simulate different collation version
-$node->safe_psql('postgres',
-	"UPDATE pg_depend SET refobjversion = 'not_a_version'"
-	. " WHERE refobjversion IS NOT NULL"
-	. " AND objid::regclass::text = 'icu1_fr';");
-
-test_index(qr/index "icu1_fr" depends on collation "fr-x-icu" version "not_a_version", but the current version is/,
-	'Different collation version warning should be raised.');
-
-$node->safe_psql('postgres', 'REINDEX TABLE icu1;');
-
-test_index(qr/^$/, 'No warning should be raised');
-
-$node->stop;
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index faf99f76b54..70133df8042 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1082,6 +1082,9 @@ SELECT collname FROM pg_collation WHERE collname LIKE 'test%';
 
 DROP SCHEMA test_schema;
 DROP ROLE regress_test_role;
+-- ALTER
+ALTER COLLATION "en-x-icu" REFRESH VERSION;
+NOTICE:  version has not changed
 -- dependencies
 CREATE COLLATION test0 FROM "C";
 CREATE TABLE collate_dep_test1 (a int, b text COLLATE test0);
@@ -1947,184 +1950,6 @@ SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
  t
 (1 row)
 
--- collation versioning support
-CREATE TYPE t_en_fr AS (fr text COLLATE "fr-x-icu", en text COLLATE "en-x-icu");
-CREATE DOMAIN d_en_fr AS t_en_fr;
-CREATE DOMAIN d_es AS text COLLATE "es-x-icu";
-CREATE TYPE t_en_fr_ga AS (en_fr t_en_fr, ga text COLLATE "ga-x-icu");
-CREATE DOMAIN d_en_fr_ga AS t_en_fr_ga;
-CREATE TYPE t_custom AS (meh text, meh2 text);
-CREATE DOMAIN d_custom AS t_custom;
-CREATE COLLATION custom (
-    LOCALE = 'fr-x-icu', PROVIDER = 'icu'
-);
-CREATE TYPE myrange AS range (subtype = text, collation = "POSIX");
-CREATE TYPE myrange_en_fr_ga AS range(subtype = t_en_fr_ga);
-CREATE TABLE collate_test (
-    id integer,
-    val text COLLATE "fr-x-icu",
-    t_en_fr t_en_fr,
-    d_en_fr d_en_fr,
-    d_es d_es,
-    t_en_fr_ga t_en_fr_ga,
-    d_en_fr_ga d_en_fr_ga,
-    d_en_fr_ga_arr d_en_fr_ga[],
-    myrange myrange,
-    myrange_en_fr_ga myrange_en_fr_ga
-);
-CREATE INDEX icuidx00_val ON collate_test(val);
--- shouldn't get duplicated dependencies
-CREATE INDEX icuidx00_val_val ON collate_test(val, val);
--- shouldn't track version
-CREATE INDEX icuidx00_val_pattern ON collate_test(val text_pattern_ops);
--- should have single dependency, no version
-CREATE INDEX icuidx00_val_pattern_val_pattern ON collate_test(val text_pattern_ops, val text_pattern_ops);
--- should have single dependency, with version
-CREATE INDEX icuidx00_val_pattern_val ON collate_test(val text_pattern_ops, val);
--- should have single dependency, with version
-CREATE INDEX icuidx00_val_val_pattern ON collate_test(val, val text_pattern_ops);
--- two rows expected, only one a version, because we don't try to merge these yet
-CREATE INDEX icuidx00_val_pattern_where ON collate_test(val text_pattern_ops) WHERE val >= val;
--- two rows expected with version, because we don't try to merge these yet
-CREATE INDEX icuidx00_val_where ON collate_test(val) WHERE val >= val;
--- two rows expected with version (expression walker + attribute)
-CREATE INDEX icuidx00_val_pattern_expr ON collate_test(val varchar_pattern_ops, (val || val));
--- two rows expected, one with a version (expression walker + attribute)
-CREATE INDEX icuidx00_val_pattern_expr_pattern ON collate_test(val varchar_pattern_ops, (val || val) text_pattern_ops);
--- should have single dependency, with version tracked
-CREATE INDEX icuidx01_t_en_fr__d_es ON collate_test (t_en_fr, d_es);
-CREATE INDEX icuidx02_d_en_fr ON collate_test (d_en_fr);
-CREATE INDEX icuidx03_t_en_fr_ga ON collate_test (t_en_fr_ga);
-CREATE INDEX icuidx04_d_en_fr_ga ON collate_test (d_en_fr_ga);
-CREATE INDEX icuidx05_d_en_fr_ga_arr ON collate_test (d_en_fr_ga_arr);
-CREATE INDEX icuidx06_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga).en_fr.fr = 'foo';
-CREATE INDEX icuidx07_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga).ga = 'foo';
-CREATE INDEX icuidx08_d_en_fr_ga ON collate_test(id) WHERE (t_en_fr_ga) = ('foo', 'bar', 'baz');
-CREATE INDEX icuidx09_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga) = ('foo', 'bar', 'baz');
-CREATE INDEX icuidx10_d_en_fr_ga_es ON collate_test(id) WHERE (d_en_fr_ga) = ('foo', 'bar', 'baz' COLLATE "es-x-icu");
-CREATE INDEX icuidx11_d_es ON collate_test(id) WHERE (d_es) = ('foo');
-CREATE INDEX icuidx12_custom ON collate_test(id) WHERE ('foo', 'bar')::d_custom = ('foo', 'bar' COLLATE custom)::d_custom;
-CREATE INDEX icuidx13_custom ON collate_test(id) WHERE ('foo' COLLATE custom, 'bar')::d_custom = ('foo', 'bar')::d_custom;
-CREATE INDEX icuidx14_myrange ON collate_test(myrange);
-CREATE INDEX icuidx15_myrange_en_fr_ga ON collate_test USING gist (myrange_en_fr_ga);
-CREATE TABLE collate_part(id integer, val text COLLATE "en-x-icu") PARTITION BY range(id);
-CREATE TABLE collate_part_0 PARTITION OF collate_part FOR VALUES FROM (0) TO (1);
-CREATE TABLE collate_part_1 PARTITION OF collate_part FOR VALUES FROM (1) TO (1000000);
-CREATE INDEX icuidx17_part ON collate_part_1 (val);
-SELECT objid::regclass::text collate "C", refobjid::regcollation::text collate "C",
-CASE
-WHEN refobjid = 'default'::regcollation THEN 'XXX' -- depends on libc version support
-WHEN refobjversion IS NULL THEN 'version not tracked'
-WHEN refobjversion = pg_collation_actual_version(refobjid) THEN 'up to date'
-ELSE 'out of date'
-END AS version
-FROM pg_depend d
-LEFT JOIN pg_class c ON c.oid = d.objid
-WHERE refclassid = 'pg_collation'::regclass
-AND coalesce(relkind, 'i') = 'i'
-AND relname LIKE 'icuidx%'
-ORDER BY 1, 2, 3;
-               objid               |  refobjid  |       version       
------------------------------------+------------+---------------------
- icuidx00_val                      | "fr-x-icu" | up to date
- icuidx00_val_pattern              | "fr-x-icu" | version not tracked
- icuidx00_val_pattern_expr         | "fr-x-icu" | up to date
- icuidx00_val_pattern_expr         | "fr-x-icu" | up to date
- icuidx00_val_pattern_expr_pattern | "fr-x-icu" | up to date
- icuidx00_val_pattern_expr_pattern | "fr-x-icu" | version not tracked
- icuidx00_val_pattern_val          | "fr-x-icu" | up to date
- icuidx00_val_pattern_val_pattern  | "fr-x-icu" | version not tracked
- icuidx00_val_pattern_where        | "fr-x-icu" | up to date
- icuidx00_val_pattern_where        | "fr-x-icu" | version not tracked
- icuidx00_val_val                  | "fr-x-icu" | up to date
- icuidx00_val_val_pattern          | "fr-x-icu" | up to date
- icuidx00_val_where                | "fr-x-icu" | up to date
- icuidx00_val_where                | "fr-x-icu" | up to date
- icuidx01_t_en_fr__d_es            | "en-x-icu" | up to date
- icuidx01_t_en_fr__d_es            | "es-x-icu" | up to date
- icuidx01_t_en_fr__d_es            | "fr-x-icu" | up to date
- icuidx02_d_en_fr                  | "en-x-icu" | up to date
- icuidx02_d_en_fr                  | "fr-x-icu" | up to date
- icuidx03_t_en_fr_ga               | "en-x-icu" | up to date
- icuidx03_t_en_fr_ga               | "fr-x-icu" | up to date
- icuidx03_t_en_fr_ga               | "ga-x-icu" | up to date
- icuidx04_d_en_fr_ga               | "en-x-icu" | up to date
- icuidx04_d_en_fr_ga               | "fr-x-icu" | up to date
- icuidx04_d_en_fr_ga               | "ga-x-icu" | up to date
- icuidx05_d_en_fr_ga_arr           | "en-x-icu" | up to date
- icuidx05_d_en_fr_ga_arr           | "fr-x-icu" | up to date
- icuidx05_d_en_fr_ga_arr           | "ga-x-icu" | up to date
- icuidx06_d_en_fr_ga               | "fr-x-icu" | up to date
- icuidx07_d_en_fr_ga               | "ga-x-icu" | up to date
- icuidx10_d_en_fr_ga_es            | "es-x-icu" | up to date
- icuidx11_d_es                     | "es-x-icu" | up to date
- icuidx12_custom                   | custom     | up to date
- icuidx13_custom                   | custom     | up to date
- icuidx15_myrange_en_fr_ga         | "en-x-icu" | up to date
- icuidx15_myrange_en_fr_ga         | "fr-x-icu" | up to date
- icuidx15_myrange_en_fr_ga         | "ga-x-icu" | up to date
- icuidx17_part                     | "en-x-icu" | up to date
-(38 rows)
-
--- Validate that REINDEX will update the stored version.
-UPDATE pg_depend SET refobjversion = 'not a version'
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text LIKE 'icuidx%'
-AND refobjversion IS NOT NULL;
-REINDEX TABLE collate_test;
-REINDEX TABLE collate_part_0;
-REINDEX TABLE collate_part_1;
-SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
- objid 
--------
-(0 rows)
-
--- Validate that REINDEX CONCURRENTLY will update the stored version.
-UPDATE pg_depend SET refobjversion = 'not a version'
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text LIKE 'icuidx%'
-AND refobjversion IS NOT NULL;
-REINDEX TABLE CONCURRENTLY collate_test;
-REINDEX TABLE CONCURRENTLY collate_part_0;
-REINDEX INDEX CONCURRENTLY icuidx17_part;
-SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
- objid 
--------
-(0 rows)
-
--- Validate that VACUUM FULL will update the stored version.
-UPDATE pg_depend SET refobjversion = 'not a version'
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text LIKE 'icuidx%'
-AND refobjversion IS NOT NULL;
-VACUUM FULL collate_test;
-VACUUM FULL collate_part_0;
-VACUUM FULL collate_part_1;
-SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
- objid 
--------
-(0 rows)
-
--- Test ALTER INDEX name ALTER COLLATION name REFRESH VERSION
-UPDATE pg_depend SET refobjversion = 'not a version'
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text = 'icuidx17_part'
-AND refobjversion IS NOT NULL;
-SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
-     objid     
----------------
- icuidx17_part
-(1 row)
-
-ALTER INDEX icuidx17_part ALTER COLLATION "en-x-icu" REFRESH VERSION;
-SELECT objid::regclass, refobjversion = 'not a version' AS ver FROM pg_depend
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text = 'icuidx17_part';
-     objid     | ver 
----------------+-----
- icuidx17_part | f
-(1 row)
-
 -- cleanup
 RESET search_path;
 SET client_min_messages TO warning;
@@ -2132,17 +1957,3 @@ DROP SCHEMA collate_tests CASCADE;
 RESET client_min_messages;
 -- leave a collation for pg_upgrade test
 CREATE COLLATION coll_icu_upgrade FROM "und-x-icu";
--- Test user-visible function for inspecting versions
-SELECT pg_collation_actual_version('"en-x-icu"'::regcollation) is not null;
- ?column? 
-----------
- t
-(1 row)
-
--- Invalid OIDs are silently ignored
-SELECT pg_collation_actual_version(0) is null;
- ?column? 
-----------
- t
-(1 row)
-
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index 580b00eea79..f06ae543e49 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1093,6 +1093,9 @@ SELECT collname FROM pg_collation WHERE collname LIKE 'test%';
 
 DROP SCHEMA test_schema;
 DROP ROLE regress_test_role;
+-- ALTER
+ALTER COLLATION "en_US" REFRESH VERSION;
+NOTICE:  version has not changed
 -- dependencies
 CREATE COLLATION test0 FROM "C";
 CREATE TABLE collate_dep_test1 (a int, b text COLLATE test0);
diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index 7f8f91b92c6..49f2a158c1f 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -2026,10 +2026,10 @@ REINDEX TABLE concur_reindex_tab; -- notice
 NOTICE:  table "concur_reindex_tab" has no indexes to reindex
 REINDEX (CONCURRENTLY) TABLE concur_reindex_tab; -- notice
 NOTICE:  table "concur_reindex_tab" has no indexes that can be reindexed concurrently
-ALTER TABLE concur_reindex_tab ADD COLUMN c2 text COLLATE "C"; -- add toast index
+ALTER TABLE concur_reindex_tab ADD COLUMN c2 text; -- add toast index
 -- Normal index with integer column
 CREATE UNIQUE INDEX concur_reindex_ind1 ON concur_reindex_tab(c1);
--- Normal index with text column (with unversioned collation)
+-- Normal index with text column
 CREATE INDEX concur_reindex_ind2 ON concur_reindex_tab(c2);
 -- UNIQUE index with expression
 CREATE UNIQUE INDEX concur_reindex_ind3 ON concur_reindex_tab(abs(c1));
@@ -2483,7 +2483,7 @@ WARNING:  cannot reindex system catalogs concurrently, skipping all
  Column |  Type   | Collation | Nullable | Default 
 --------+---------+-----------+----------+---------
  c1     | integer |           | not null | 
- c2     | text    | C         |          | 
+ c2     | text    |           |          | 
 Indexes:
     "concur_reindex_ind1" PRIMARY KEY, btree (c1)
     "concur_reindex_ind2" btree (c2)
diff --git a/src/test/regress/expected/misc_sanity.out b/src/test/regress/expected/misc_sanity.out
index 9ebe28a78da..a67f40198a4 100644
--- a/src/test/regress/expected/misc_sanity.out
+++ b/src/test/regress/expected/misc_sanity.out
@@ -18,8 +18,8 @@ WHERE refclassid = 0 OR refobjid = 0 OR
       deptype NOT IN ('a', 'e', 'i', 'n', 'p') OR
       (deptype != 'p' AND (classid = 0 OR objid = 0)) OR
       (deptype = 'p' AND (classid != 0 OR objid != 0 OR objsubid != 0));
- classid | objid | objsubid | refclassid | refobjid | refobjsubid | deptype | refobjversion 
----------+-------+----------+------------+----------+-------------+---------+---------------
+ classid | objid | objsubid | refclassid | refobjid | refobjsubid | deptype 
+---------+-------+----------+------------+----------+-------------+---------
 (0 rows)
 
 -- **************** pg_shdepend ****************
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 4c71f4d249e..9cee3d0042b 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -405,6 +405,11 @@ DROP SCHEMA test_schema;
 DROP ROLE regress_test_role;
 
 
+-- ALTER
+
+ALTER COLLATION "en-x-icu" REFRESH VERSION;
+
+
 -- dependencies
 
 CREATE COLLATION test0 FROM "C";
@@ -742,134 +747,6 @@ INSERT INTO test33 VALUES (2, 'DEF');
 -- they end up in the same partition (but it's platform-dependent which one)
 SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
 
--- collation versioning support
-CREATE TYPE t_en_fr AS (fr text COLLATE "fr-x-icu", en text COLLATE "en-x-icu");
-CREATE DOMAIN d_en_fr AS t_en_fr;
-CREATE DOMAIN d_es AS text COLLATE "es-x-icu";
-CREATE TYPE t_en_fr_ga AS (en_fr t_en_fr, ga text COLLATE "ga-x-icu");
-CREATE DOMAIN d_en_fr_ga AS t_en_fr_ga;
-CREATE TYPE t_custom AS (meh text, meh2 text);
-CREATE DOMAIN d_custom AS t_custom;
-
-CREATE COLLATION custom (
-    LOCALE = 'fr-x-icu', PROVIDER = 'icu'
-);
-
-CREATE TYPE myrange AS range (subtype = text, collation = "POSIX");
-CREATE TYPE myrange_en_fr_ga AS range(subtype = t_en_fr_ga);
-
-CREATE TABLE collate_test (
-    id integer,
-    val text COLLATE "fr-x-icu",
-    t_en_fr t_en_fr,
-    d_en_fr d_en_fr,
-    d_es d_es,
-    t_en_fr_ga t_en_fr_ga,
-    d_en_fr_ga d_en_fr_ga,
-    d_en_fr_ga_arr d_en_fr_ga[],
-    myrange myrange,
-    myrange_en_fr_ga myrange_en_fr_ga
-);
-
-CREATE INDEX icuidx00_val ON collate_test(val);
--- shouldn't get duplicated dependencies
-CREATE INDEX icuidx00_val_val ON collate_test(val, val);
--- shouldn't track version
-CREATE INDEX icuidx00_val_pattern ON collate_test(val text_pattern_ops);
--- should have single dependency, no version
-CREATE INDEX icuidx00_val_pattern_val_pattern ON collate_test(val text_pattern_ops, val text_pattern_ops);
--- should have single dependency, with version
-CREATE INDEX icuidx00_val_pattern_val ON collate_test(val text_pattern_ops, val);
--- should have single dependency, with version
-CREATE INDEX icuidx00_val_val_pattern ON collate_test(val, val text_pattern_ops);
--- two rows expected, only one a version, because we don't try to merge these yet
-CREATE INDEX icuidx00_val_pattern_where ON collate_test(val text_pattern_ops) WHERE val >= val;
--- two rows expected with version, because we don't try to merge these yet
-CREATE INDEX icuidx00_val_where ON collate_test(val) WHERE val >= val;
--- two rows expected with version (expression walker + attribute)
-CREATE INDEX icuidx00_val_pattern_expr ON collate_test(val varchar_pattern_ops, (val || val));
--- two rows expected, one with a version (expression walker + attribute)
-CREATE INDEX icuidx00_val_pattern_expr_pattern ON collate_test(val varchar_pattern_ops, (val || val) text_pattern_ops);
--- should have single dependency, with version tracked
-CREATE INDEX icuidx01_t_en_fr__d_es ON collate_test (t_en_fr, d_es);
-CREATE INDEX icuidx02_d_en_fr ON collate_test (d_en_fr);
-CREATE INDEX icuidx03_t_en_fr_ga ON collate_test (t_en_fr_ga);
-CREATE INDEX icuidx04_d_en_fr_ga ON collate_test (d_en_fr_ga);
-CREATE INDEX icuidx05_d_en_fr_ga_arr ON collate_test (d_en_fr_ga_arr);
-CREATE INDEX icuidx06_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga).en_fr.fr = 'foo';
-CREATE INDEX icuidx07_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga).ga = 'foo';
-CREATE INDEX icuidx08_d_en_fr_ga ON collate_test(id) WHERE (t_en_fr_ga) = ('foo', 'bar', 'baz');
-CREATE INDEX icuidx09_d_en_fr_ga ON collate_test(id) WHERE (d_en_fr_ga) = ('foo', 'bar', 'baz');
-CREATE INDEX icuidx10_d_en_fr_ga_es ON collate_test(id) WHERE (d_en_fr_ga) = ('foo', 'bar', 'baz' COLLATE "es-x-icu");
-CREATE INDEX icuidx11_d_es ON collate_test(id) WHERE (d_es) = ('foo');
-CREATE INDEX icuidx12_custom ON collate_test(id) WHERE ('foo', 'bar')::d_custom = ('foo', 'bar' COLLATE custom)::d_custom;
-CREATE INDEX icuidx13_custom ON collate_test(id) WHERE ('foo' COLLATE custom, 'bar')::d_custom = ('foo', 'bar')::d_custom;
-CREATE INDEX icuidx14_myrange ON collate_test(myrange);
-CREATE INDEX icuidx15_myrange_en_fr_ga ON collate_test USING gist (myrange_en_fr_ga);
-
-CREATE TABLE collate_part(id integer, val text COLLATE "en-x-icu") PARTITION BY range(id);
-CREATE TABLE collate_part_0 PARTITION OF collate_part FOR VALUES FROM (0) TO (1);
-CREATE TABLE collate_part_1 PARTITION OF collate_part FOR VALUES FROM (1) TO (1000000);
-CREATE INDEX icuidx17_part ON collate_part_1 (val);
-
-SELECT objid::regclass::text collate "C", refobjid::regcollation::text collate "C",
-CASE
-WHEN refobjid = 'default'::regcollation THEN 'XXX' -- depends on libc version support
-WHEN refobjversion IS NULL THEN 'version not tracked'
-WHEN refobjversion = pg_collation_actual_version(refobjid) THEN 'up to date'
-ELSE 'out of date'
-END AS version
-FROM pg_depend d
-LEFT JOIN pg_class c ON c.oid = d.objid
-WHERE refclassid = 'pg_collation'::regclass
-AND coalesce(relkind, 'i') = 'i'
-AND relname LIKE 'icuidx%'
-ORDER BY 1, 2, 3;
-
--- Validate that REINDEX will update the stored version.
-UPDATE pg_depend SET refobjversion = 'not a version'
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text LIKE 'icuidx%'
-AND refobjversion IS NOT NULL;
-
-REINDEX TABLE collate_test;
-REINDEX TABLE collate_part_0;
-REINDEX TABLE collate_part_1;
-
-SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
-
--- Validate that REINDEX CONCURRENTLY will update the stored version.
-UPDATE pg_depend SET refobjversion = 'not a version'
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text LIKE 'icuidx%'
-AND refobjversion IS NOT NULL;
-REINDEX TABLE CONCURRENTLY collate_test;
-REINDEX TABLE CONCURRENTLY collate_part_0;
-REINDEX INDEX CONCURRENTLY icuidx17_part;
-
-SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
-
--- Validate that VACUUM FULL will update the stored version.
-UPDATE pg_depend SET refobjversion = 'not a version'
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text LIKE 'icuidx%'
-AND refobjversion IS NOT NULL;
-VACUUM FULL collate_test;
-VACUUM FULL collate_part_0;
-VACUUM FULL collate_part_1;
-
-SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
-
--- Test ALTER INDEX name ALTER COLLATION name REFRESH VERSION
-UPDATE pg_depend SET refobjversion = 'not a version'
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text = 'icuidx17_part'
-AND refobjversion IS NOT NULL;
-SELECT objid::regclass FROM pg_depend WHERE refobjversion = 'not a version';
-ALTER INDEX icuidx17_part ALTER COLLATION "en-x-icu" REFRESH VERSION;
-SELECT objid::regclass, refobjversion = 'not a version' AS ver FROM pg_depend
-WHERE refclassid = 'pg_collation'::regclass
-AND objid::regclass::text = 'icuidx17_part';
 
 -- cleanup
 RESET search_path;
@@ -879,8 +756,3 @@ RESET client_min_messages;
 
 -- leave a collation for pg_upgrade test
 CREATE COLLATION coll_icu_upgrade FROM "und-x-icu";
-
--- Test user-visible function for inspecting versions
-SELECT pg_collation_actual_version('"en-x-icu"'::regcollation) is not null;
--- Invalid OIDs are silently ignored
-SELECT pg_collation_actual_version(0) is null;
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index c697c994880..cbbd2203e41 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -406,6 +406,11 @@ DROP SCHEMA test_schema;
 DROP ROLE regress_test_role;
 
 
+-- ALTER
+
+ALTER COLLATION "en_US" REFRESH VERSION;
+
+
 -- dependencies
 
 CREATE COLLATION test0 FROM "C";
diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql
index 51c9a121514..8bc76f7c6f1 100644
--- a/src/test/regress/sql/create_index.sql
+++ b/src/test/regress/sql/create_index.sql
@@ -797,10 +797,10 @@ CREATE TABLE concur_reindex_tab (c1 int);
 -- REINDEX
 REINDEX TABLE concur_reindex_tab; -- notice
 REINDEX (CONCURRENTLY) TABLE concur_reindex_tab; -- notice
-ALTER TABLE concur_reindex_tab ADD COLUMN c2 text COLLATE "C"; -- add toast index
+ALTER TABLE concur_reindex_tab ADD COLUMN c2 text; -- add toast index
 -- Normal index with integer column
 CREATE UNIQUE INDEX concur_reindex_ind1 ON concur_reindex_tab(c1);
--- Normal index with text column (with unversioned collation)
+-- Normal index with text column
 CREATE INDEX concur_reindex_ind2 ON concur_reindex_tab(c2);
 -- UNIQUE index with expression
 CREATE UNIQUE INDEX concur_reindex_ind3 ON concur_reindex_tab(abs(c1));
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 878b67a276d..0f197a9c8db 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2948,8 +2948,6 @@ dlist_head
 dlist_iter
 dlist_mutable_iter
 dlist_node
-do_collation_version_check_context
-do_collation_version_update_context
 ds_state
 dsa_area
 dsa_area_control