Add temporal FOREIGN KEY contraints

Add PERIOD clause to foreign key constraint definitions.  This is
supported for range and multirange types.  Temporal foreign keys check
for range containment instead of equality.

This feature matches the behavior of the SQL standard temporal foreign
keys, but it works on PostgreSQL's native ranges instead of SQL's
"periods", which don't exist in PostgreSQL (yet).

Reference actions ON {UPDATE,DELETE} {CASCADE,SET NULL,SET DEFAULT}
are not supported yet.

Author: Paul A. Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CA+renyUApHgSZF9-nd-a0+OPGharLQLO=mDHcY4_qQ0+noCUVg@mail.gmail.com

1 files changed, 10 insertions, 7 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 4a7402e09ef..a51717e36ce 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -338,7 +338,7 @@ static char *pg_get_viewdef_worker(Oid viewoid,
 								   int prettyFlags, int wrapColumn);
 static char *pg_get_triggerdef_worker(Oid trigid, bool pretty);
 static int	decompile_column_index_array(Datum column_index_array, Oid relId,
-										 StringInfo buf);
+										 bool withPeriod, StringInfo buf);
 static char *pg_get_ruledef_worker(Oid ruleoid, int prettyFlags);
 static char *pg_get_indexdef_worker(Oid indexrelid, int colno,
 									const Oid *excludeOps,
@@ -2253,7 +2253,8 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
 				val = SysCacheGetAttrNotNull(CONSTROID, tup,
 											 Anum_pg_constraint_conkey);
 
-				decompile_column_index_array(val, conForm->conrelid, &buf);
+				/* If it is a temporal foreign key then it uses PERIOD. */
+				decompile_column_index_array(val, conForm->conrelid, conForm->conperiod, &buf);
 
 				/* add foreign relation name */
 				appendStringInfo(&buf, ") REFERENCES %s(",
@@ -2264,7 +2265,7 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
 				val = SysCacheGetAttrNotNull(CONSTROID, tup,
 											 Anum_pg_constraint_confkey);
 
-				decompile_column_index_array(val, conForm->confrelid, &buf);
+				decompile_column_index_array(val, conForm->confrelid, conForm->conperiod, &buf);
 
 				appendStringInfoChar(&buf, ')');
 
@@ -2350,7 +2351,7 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
 				if (!isnull)
 				{
 					appendStringInfoString(&buf, " (");
-					decompile_column_index_array(val, conForm->conrelid, &buf);
+					decompile_column_index_array(val, conForm->conrelid, false, &buf);
 					appendStringInfoChar(&buf, ')');
 				}
 
@@ -2385,7 +2386,7 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
 				val = SysCacheGetAttrNotNull(CONSTROID, tup,
 											 Anum_pg_constraint_conkey);
 
-				keyatts = decompile_column_index_array(val, conForm->conrelid, &buf);
+				keyatts = decompile_column_index_array(val, conForm->conrelid, false, &buf);
 				if (conForm->conperiod)
 					appendStringInfoString(&buf, " WITHOUT OVERLAPS");
 
@@ -2591,7 +2592,7 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
  */
 static int
 decompile_column_index_array(Datum column_index_array, Oid relId,
-							 StringInfo buf)
+							 bool withPeriod, StringInfo buf)
 {
 	Datum	   *keys;
 	int			nKeys;
@@ -2610,7 +2611,9 @@ decompile_column_index_array(Datum column_index_array, Oid relId,
 		if (j == 0)
 			appendStringInfoString(buf, quote_identifier(colName));
 		else
-			appendStringInfo(buf, ", %s", quote_identifier(colName));
+			appendStringInfo(buf, ", %s%s",
+							 (withPeriod && j == nKeys - 1) ? "PERIOD " : "",
+							 quote_identifier(colName));
 	}
 
 	return nKeys;