Revise collation derivation method and expression-tree representation.

All expression nodes now have an explicit output-collation field, unless
they are known to only return a noncollatable data type (such as boolean
or record).  Also, nodes that can invoke collation-aware functions store
a separate field that is the collation value to pass to the function.
This avoids confusion that arises when a function has collatable inputs
and noncollatable output type, or vice versa.

Also, replace the parser's on-the-fly collation assignment method with
a post-pass over the completed expression tree.  This allows us to use
a more complex (and hopefully more nearly spec-compliant) assignment
rule without paying for it in extra storage in every expression node.

Fix assorted bugs in the planner's handling of collations by making
collation one of the defining properties of an EquivalenceClass and
by converting CollateExprs into discardable RelabelType nodes during
expression preprocessing.

1 files changed, 6 insertions, 6 deletions

diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 55fce94b321..e60db7813a4 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -732,7 +732,6 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 		int			op_strategy;	/* operator's strategy number */
 		Oid			op_lefttype;	/* operator's declared input types */
 		Oid			op_righttype;
-		Oid			collation;
 		Expr	   *leftop;		/* expr on lhs of operator */
 		Expr	   *rightop;	/* expr on rhs ... */
 		AttrNumber	varattno;	/* att number used in scan */
@@ -833,7 +832,7 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 								   opfuncid,	/* reg proc to use */
 								   scanvalue);	/* constant */
 			ScanKeyEntryInitializeCollation(this_scan_key,
-											((OpExpr *) clause)->collid);
+											((OpExpr *) clause)->inputcollid);
 		}
 		else if (IsA(clause, RowCompareExpr))
 		{
@@ -842,7 +841,7 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 			ListCell   *largs_cell = list_head(rc->largs);
 			ListCell   *rargs_cell = list_head(rc->rargs);
 			ListCell   *opnos_cell = list_head(rc->opnos);
-			ListCell   *collids_cell = list_head(rc->collids);
+			ListCell   *collids_cell = list_head(rc->inputcollids);
 			ScanKey		first_sub_key;
 			int			n_sub_key;
 
@@ -858,6 +857,7 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 				ScanKey		this_sub_key = &first_sub_key[n_sub_key];
 				int			flags = SK_ROW_MEMBER;
 				Datum		scanvalue;
+				Oid			inputcollation;
 
 				/*
 				 * leftop should be the index key Var, possibly relabeled
@@ -901,7 +901,7 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 											 op_righttype,
 											 BTORDER_PROC);
 
-				collation = lfirst_oid(collids_cell);
+				inputcollation = lfirst_oid(collids_cell);
 				collids_cell = lnext(collids_cell);
 
 				/*
@@ -960,7 +960,7 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 									   opfuncid,		/* reg proc to use */
 									   scanvalue);		/* constant */
 				ScanKeyEntryInitializeCollation(this_sub_key,
-												collation);
+												inputcollation);
 				n_sub_key++;
 			}
 
@@ -1045,7 +1045,7 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index, Index scanrelid,
 								   opfuncid,	/* reg proc to use */
 								   (Datum) 0);	/* constant */
 			ScanKeyEntryInitializeCollation(this_scan_key,
-											saop->collid);
+											saop->inputcollid);
 		}
 		else if (IsA(clause, NullTest))
 		{