Allow foreign tables to participate in inheritance.

Foreign tables can now be inheritance children, or parents.  Much of the
system was already ready for this, but we had to fix a few things of
course, mostly in the area of planner and executor handling of row locks.

As side effects of this, allow foreign tables to have NOT VALID CHECK
constraints (and hence to accept ALTER ... VALIDATE CONSTRAINT), and to
accept ALTER SET STORAGE and ALTER SET WITH/WITHOUT OIDS.  Continuing to
disallow these things would've required bizarre and inconsistent special
cases in inheritance behavior.  Since foreign tables don't enforce CHECK
constraints anyway, a NOT VALID one is a complete no-op, but that doesn't
mean we shouldn't allow it.  And it's possible that some FDWs might have
use for SET STORAGE or SET WITH OIDS, though doubtless they will be no-ops
for most.

An additional change in support of this is that when a ModifyTable node
has multiple target tables, they will all now be explicitly identified
in EXPLAIN output, for example:

 Update on pt1  (cost=0.00..321.05 rows=3541 width=46)
   Update on pt1
   Foreign Update on ft1
   Foreign Update on ft2
   Update on child3
   ->  Seq Scan on pt1  (cost=0.00..0.00 rows=1 width=46)
   ->  Foreign Scan on ft1  (cost=100.00..148.03 rows=1170 width=46)
   ->  Foreign Scan on ft2  (cost=100.00..148.03 rows=1170 width=46)
   ->  Seq Scan on child3  (cost=0.00..25.00 rows=1200 width=46)

This was done mainly to provide an unambiguous place to attach "Remote SQL"
fields, but it is useful for inherited updates even when no foreign tables
are involved.

Shigeru Hanada and Etsuro Fujita, reviewed by Ashutosh Bapat and Kyotaro
Horiguchi, some additional hacking by me

1 files changed, 39 insertions, 40 deletions

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 13ceffae5c4..ad7e2072908 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -814,21 +814,22 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 		if (rc->isParent)
 			continue;
 
+		/* get relation's OID (will produce InvalidOid if subquery) */
+		relid = getrelid(rc->rti, rangeTable);
+
 		switch (rc->markType)
 		{
 			case ROW_MARK_EXCLUSIVE:
 			case ROW_MARK_NOKEYEXCLUSIVE:
 			case ROW_MARK_SHARE:
 			case ROW_MARK_KEYSHARE:
-				relid = getrelid(rc->rti, rangeTable);
 				relation = heap_open(relid, RowShareLock);
 				break;
 			case ROW_MARK_REFERENCE:
-				relid = getrelid(rc->rti, rangeTable);
 				relation = heap_open(relid, AccessShareLock);
 				break;
 			case ROW_MARK_COPY:
-				/* there's no real table here ... */
+				/* no physical table access is required */
 				relation = NULL;
 				break;
 			default:
@@ -843,6 +844,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 
 		erm = (ExecRowMark *) palloc(sizeof(ExecRowMark));
 		erm->relation = relation;
+		erm->relid = relid;
 		erm->rti = rc->rti;
 		erm->prti = rc->prti;
 		erm->rowmarkId = rc->rowmarkId;
@@ -1911,21 +1913,9 @@ ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist)
 	aerm->rowmark = erm;
 
 	/* Look up the resjunk columns associated with this rowmark */
-	if (erm->relation)
+	if (erm->markType != ROW_MARK_COPY)
 	{
-		Assert(erm->markType != ROW_MARK_COPY);
-
-		/* if child rel, need tableoid */
-		if (erm->rti != erm->prti)
-		{
-			snprintf(resname, sizeof(resname), "tableoid%u", erm->rowmarkId);
-			aerm->toidAttNo = ExecFindJunkAttributeInTlist(targetlist,
-														   resname);
-			if (!AttributeNumberIsValid(aerm->toidAttNo))
-				elog(ERROR, "could not find junk %s column", resname);
-		}
-
-		/* always need ctid for real relations */
+		/* need ctid for all methods other than COPY */
 		snprintf(resname, sizeof(resname), "ctid%u", erm->rowmarkId);
 		aerm->ctidAttNo = ExecFindJunkAttributeInTlist(targetlist,
 													   resname);
@@ -1934,8 +1924,7 @@ ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist)
 	}
 	else
 	{
-		Assert(erm->markType == ROW_MARK_COPY);
-
+		/* need wholerow if COPY */
 		snprintf(resname, sizeof(resname), "wholerow%u", erm->rowmarkId);
 		aerm->wholeAttNo = ExecFindJunkAttributeInTlist(targetlist,
 														resname);
@@ -1943,6 +1932,16 @@ ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist)
 			elog(ERROR, "could not find junk %s column", resname);
 	}
 
+	/* if child rel, need tableoid */
+	if (erm->rti != erm->prti)
+	{
+		snprintf(resname, sizeof(resname), "tableoid%u", erm->rowmarkId);
+		aerm->toidAttNo = ExecFindJunkAttributeInTlist(targetlist,
+													   resname);
+		if (!AttributeNumberIsValid(aerm->toidAttNo))
+			elog(ERROR, "could not find junk %s column", resname);
+	}
+
 	return aerm;
 }
 
@@ -2375,31 +2374,32 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
 		/* clear any leftover test tuple for this rel */
 		EvalPlanQualSetTuple(epqstate, erm->rti, NULL);
 
-		if (erm->relation)
+		/* if child rel, must check whether it produced this row */
+		if (erm->rti != erm->prti)
 		{
-			Buffer		buffer;
+			Oid			tableoid;
 
-			Assert(erm->markType == ROW_MARK_REFERENCE);
+			datum = ExecGetJunkAttribute(epqstate->origslot,
+										 aerm->toidAttNo,
+										 &isNull);
+			/* non-locked rels could be on the inside of outer joins */
+			if (isNull)
+				continue;
+			tableoid = DatumGetObjectId(datum);
 
-			/* if child rel, must check whether it produced this row */
-			if (erm->rti != erm->prti)
+			Assert(OidIsValid(erm->relid));
+			if (tableoid != erm->relid)
 			{
-				Oid			tableoid;
+				/* this child is inactive right now */
+				continue;
+			}
+		}
 
-				datum = ExecGetJunkAttribute(epqstate->origslot,
-											 aerm->toidAttNo,
-											 &isNull);
-				/* non-locked rels could be on the inside of outer joins */
-				if (isNull)
-					continue;
-				tableoid = DatumGetObjectId(datum);
+		if (erm->markType == ROW_MARK_REFERENCE)
+		{
+			Buffer		buffer;
 
-				if (tableoid != RelationGetRelid(erm->relation))
-				{
-					/* this child is inactive right now */
-					continue;
-				}
-			}
+			Assert(erm->relation != NULL);
 
 			/* fetch the tuple's ctid */
 			datum = ExecGetJunkAttribute(epqstate->origslot,
@@ -2439,8 +2439,7 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
 			tuple.t_len = HeapTupleHeaderGetDatumLength(td);
 			ItemPointerSetInvalid(&(tuple.t_self));
 			/* relation might be a foreign table, if so provide tableoid */
-			tuple.t_tableOid = getrelid(erm->rti,
-										epqstate->estate->es_range_table);
+			tuple.t_tableOid = erm->relid;
 			tuple.t_data = td;
 
 			/* copy and store tuple */