Function ATExecSetRelOptions

src/backend/commands/tablecmds.c:16125–16386

* Set, reset, or replace reloptions. * * GPDB specific arguments: * aoopt_changed: whether any AO storage options have been changed in this function. * newam: the new AM if we will change the table AM. It's InvalidOid if no change is needed. */

 * 	newam: the new AM if we will change the table AM. It's InvalidOid if no change is needed.
 */
static void
ATExecSetRelOptions(Relation rel, List *defList, AlterTableType operation,
					bool *aoopt_changed, Oid newAccessMethod, LOCKMODE lockmode)
{
	Oid			relid;
	Relation	pgclass;
	HeapTuple	tuple;
	HeapTuple	newtuple;
	Datum		datum;
	bool		isnull;
	Datum		newOptions;
	Datum		repl_val[Natts_pg_class];
	bool		repl_null[Natts_pg_class];
	bool		repl_repl[Natts_pg_class];
	const TableAmRoutine * newAM;
	static char *validnsps[] = HEAP_RELOPT_NAMESPACES;

	if (defList == NIL && operation != AT_ReplaceRelOptions)
		return;					/* nothing to do */


	/* If we are changing access method, simply remove all the existing ones. */
	if (OidIsValid(newAccessMethod))
	{
		newAM = GetTableAmRoutineByAmId(newAccessMethod);
		clear_rel_opts(rel);
	} else
		newAM = NULL;

	pgclass = table_open(RelationRelationId, RowExclusiveLock);

	/* Fetch heap tuple */
	relid = RelationGetRelid(rel);
	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
	if (!HeapTupleIsValid(tuple))
		elog(ERROR, "cache lookup failed for relation %u", relid);

	if (operation == AT_ReplaceRelOptions)
	{
		/*
		 * If we're supposed to replace the reloptions list, we just 
		 * pretend there were none before.
		 */
		datum = (Datum) 0;
		isnull = true;
	}
	else
	{
		/* Get the old reloptions */
		datum = SysCacheGetAttr(RELOID, tuple, Anum_pg_class_reloptions,
								&isnull);
	}

	if (defList != NIL)
	{
		ListCell   *cell;

		foreach(cell, defList)