Refactor duplicate code into DeconstructFkConstraintRow

My commit 3de241dba86f introduced some code (in tablecmds.c) to obtain
data from a pg_constraint row for a foreign key, that already existed in
ri_triggers.c.  Split it out into its own routine in pg_constraint.c,
where it naturally belongs.

No functional code changes, only code movement.

Backpatch to pg11, because a future bugfix is simpler after this.

2 files changed, 12 insertions, 138 deletions

diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index e606eb342fd..0c1ee8d1f69 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -2189,10 +2189,6 @@ ri_LoadConstraintInfo(Oid constraintOid)
 	bool		found;
 	HeapTuple	tup;
 	Form_pg_constraint conForm;
-	Datum		adatum;
-	bool		isNull;
-	ArrayType  *arr;
-	int			numkeys;
 
 	/*
 	 * On the first call initialize the hashtable
@@ -2234,84 +2230,13 @@ ri_LoadConstraintInfo(Oid constraintOid)
 	riinfo->confdeltype = conForm->confdeltype;
 	riinfo->confmatchtype = conForm->confmatchtype;
 
-	/*
-	 * We expect the arrays to be 1-D arrays of the right types; verify that.
-	 * We don't need to use deconstruct_array() since the array data is just
-	 * going to look like a C array of values.
-	 */
-	adatum = SysCacheGetAttr(CONSTROID, tup,
-							 Anum_pg_constraint_conkey, &isNull);
-	if (isNull)
-		elog(ERROR, "null conkey for constraint %u", constraintOid);
-	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
-	if (ARR_NDIM(arr) != 1 ||
-		ARR_HASNULL(arr) ||
-		ARR_ELEMTYPE(arr) != INT2OID)
-		elog(ERROR, "conkey is not a 1-D smallint array");
-	numkeys = ARR_DIMS(arr)[0];
-	if (numkeys <= 0 || numkeys > RI_MAX_NUMKEYS)
-		elog(ERROR, "foreign key constraint cannot have %d columns", numkeys);
-	riinfo->nkeys = numkeys;
-	memcpy(riinfo->fk_attnums, ARR_DATA_PTR(arr), numkeys * sizeof(int16));
-	if ((Pointer) arr != DatumGetPointer(adatum))
-		pfree(arr);				/* free de-toasted copy, if any */
-
-	adatum = SysCacheGetAttr(CONSTROID, tup,
-							 Anum_pg_constraint_confkey, &isNull);
-	if (isNull)
-		elog(ERROR, "null confkey for constraint %u", constraintOid);
-	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
-	if (ARR_NDIM(arr) != 1 ||
-		ARR_DIMS(arr)[0] != numkeys ||
-		ARR_HASNULL(arr) ||
-		ARR_ELEMTYPE(arr) != INT2OID)
-		elog(ERROR, "confkey is not a 1-D smallint array");
-	memcpy(riinfo->pk_attnums, ARR_DATA_PTR(arr), numkeys * sizeof(int16));
-	if ((Pointer) arr != DatumGetPointer(adatum))
-		pfree(arr);				/* free de-toasted copy, if any */
-
-	adatum = SysCacheGetAttr(CONSTROID, tup,
-							 Anum_pg_constraint_conpfeqop, &isNull);
-	if (isNull)
-		elog(ERROR, "null conpfeqop for constraint %u", constraintOid);
-	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
-	/* see TryReuseForeignKey if you change the test below */
-	if (ARR_NDIM(arr) != 1 ||
-		ARR_DIMS(arr)[0] != numkeys ||
-		ARR_HASNULL(arr) ||
-		ARR_ELEMTYPE(arr) != OIDOID)
-		elog(ERROR, "conpfeqop is not a 1-D Oid array");
-	memcpy(riinfo->pf_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
-	if ((Pointer) arr != DatumGetPointer(adatum))
-		pfree(arr);				/* free de-toasted copy, if any */
-
-	adatum = SysCacheGetAttr(CONSTROID, tup,
-							 Anum_pg_constraint_conppeqop, &isNull);
-	if (isNull)
-		elog(ERROR, "null conppeqop for constraint %u", constraintOid);
-	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
-	if (ARR_NDIM(arr) != 1 ||
-		ARR_DIMS(arr)[0] != numkeys ||
-		ARR_HASNULL(arr) ||
-		ARR_ELEMTYPE(arr) != OIDOID)
-		elog(ERROR, "conppeqop is not a 1-D Oid array");
-	memcpy(riinfo->pp_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
-	if ((Pointer) arr != DatumGetPointer(adatum))
-		pfree(arr);				/* free de-toasted copy, if any */
-
-	adatum = SysCacheGetAttr(CONSTROID, tup,
-							 Anum_pg_constraint_conffeqop, &isNull);
-	if (isNull)
-		elog(ERROR, "null conffeqop for constraint %u", constraintOid);
-	arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
-	if (ARR_NDIM(arr) != 1 ||
-		ARR_DIMS(arr)[0] != numkeys ||
-		ARR_HASNULL(arr) ||
-		ARR_ELEMTYPE(arr) != OIDOID)
-		elog(ERROR, "conffeqop is not a 1-D Oid array");
-	memcpy(riinfo->ff_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
-	if ((Pointer) arr != DatumGetPointer(adatum))
-		pfree(arr);				/* free de-toasted copy, if any */
+	DeconstructFkConstraintRow(tup,
+							   &riinfo->nkeys,
+							   riinfo->fk_attnums,
+							   riinfo->pk_attnums,
+							   riinfo->pf_eq_oprs,
+							   riinfo->pp_eq_oprs,
+							   riinfo->ff_eq_oprs);
 
 	ReleaseSysCache(tup);
 
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index e3b1473e6c9..7ea371a3c71 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -4125,10 +4125,6 @@ RelationGetFKeyList(Relation relation)
 	{
 		Form_pg_constraint constraint = (Form_pg_constraint) GETSTRUCT(htup);
 		ForeignKeyCacheInfo *info;
-		Datum		adatum;
-		bool		isnull;
-		ArrayType  *arr;
-		int			nelem;
 
 		/* consider only foreign keys */
 		if (constraint->contype != CONSTRAINT_FOREIGN)
@@ -4139,58 +4135,11 @@ RelationGetFKeyList(Relation relation)
 		info->conrelid = constraint->conrelid;
 		info->confrelid = constraint->confrelid;
 
-		/* Extract data from conkey field */
-		adatum = fastgetattr(htup, Anum_pg_constraint_conkey,
-							 conrel->rd_att, &isnull);
-		if (isnull)
-			elog(ERROR, "null conkey for rel %s",
-				 RelationGetRelationName(relation));
-
-		arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
-		nelem = ARR_DIMS(arr)[0];
-		if (ARR_NDIM(arr) != 1 ||
-			nelem < 1 ||
-			nelem > INDEX_MAX_KEYS ||
-			ARR_HASNULL(arr) ||
-			ARR_ELEMTYPE(arr) != INT2OID)
-			elog(ERROR, "conkey is not a 1-D smallint array");
-
-		info->nkeys = nelem;
-		memcpy(info->conkey, ARR_DATA_PTR(arr), nelem * sizeof(AttrNumber));
-
-		/* Likewise for confkey */
-		adatum = fastgetattr(htup, Anum_pg_constraint_confkey,
-							 conrel->rd_att, &isnull);
-		if (isnull)
-			elog(ERROR, "null confkey for rel %s",
-				 RelationGetRelationName(relation));
-
-		arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
-		nelem = ARR_DIMS(arr)[0];
-		if (ARR_NDIM(arr) != 1 ||
-			nelem != info->nkeys ||
-			ARR_HASNULL(arr) ||
-			ARR_ELEMTYPE(arr) != INT2OID)
-			elog(ERROR, "confkey is not a 1-D smallint array");
-
-		memcpy(info->confkey, ARR_DATA_PTR(arr), nelem * sizeof(AttrNumber));
-
-		/* Likewise for conpfeqop */
-		adatum = fastgetattr(htup, Anum_pg_constraint_conpfeqop,
-							 conrel->rd_att, &isnull);
-		if (isnull)
-			elog(ERROR, "null conpfeqop for rel %s",
-				 RelationGetRelationName(relation));
-
-		arr = DatumGetArrayTypeP(adatum);	/* ensure not toasted */
-		nelem = ARR_DIMS(arr)[0];
-		if (ARR_NDIM(arr) != 1 ||
-			nelem != info->nkeys ||
-			ARR_HASNULL(arr) ||
-			ARR_ELEMTYPE(arr) != OIDOID)
-			elog(ERROR, "conpfeqop is not a 1-D OID array");
-
-		memcpy(info->conpfeqop, ARR_DATA_PTR(arr), nelem * sizeof(Oid));
+		DeconstructFkConstraintRow(htup, &info->nkeys,
+								   info->conkey,
+								   info->confkey,
+								   info->conpfeqop,
+								   NULL, NULL);
 
 		/* Add FK's node to the result list */
 		result = lappend(result, info);