Function ExecLookupResultRelByOid

src/backend/executor/nodeModifyTable.c:3075–3118

* ExecLookupResultRelByOid * If the table with given OID is among the result relations to be * updated by the given ModifyTable node, return its ResultRelInfo. * * If not found, return NULL if missing_ok, else raise error. * * If update_cache is true, then upon successful lookup, update the node's * one-element cache. ONLY ExecModifyTable may pass true for this. */

 * one-element cache.  ONLY ExecModifyTable may pass true for this.
 */
ResultRelInfo *
ExecLookupResultRelByOid(ModifyTableState *node, Oid resultoid,
						 bool missing_ok, bool update_cache)
{
	if (node->mt_resultOidHash)
	{
		/* Use the pre-built hash table to locate the rel */
		MTTargetRelLookup *mtlookup;

		mtlookup = (MTTargetRelLookup *)
			hash_search(node->mt_resultOidHash, &resultoid, HASH_FIND, NULL);
		if (mtlookup)
		{
			if (update_cache)
			{
				node->mt_lastResultOid = resultoid;
				node->mt_lastResultIndex = mtlookup->relationIndex;
			}
			return node->resultRelInfo + mtlookup->relationIndex;
		}
	}
	else
	{
		/* With few target rels, just search the ResultRelInfo array */
		for (int ndx = 0; ndx < node->mt_nrels; ndx++)
		{
			ResultRelInfo *rInfo = node->resultRelInfo + ndx;

			if (RelationGetRelid(rInfo->ri_RelationDesc) == resultoid)
			{
				if (update_cache)
				{
					node->mt_lastResultOid = resultoid;
					node->mt_lastResultIndex = ndx;
				}
				return rInfo;
			}
		}
	}

	if (!missing_ok)
		elog(ERROR, "incorrect result relation OID %u", resultoid);
	return NULL;
}

/* ----------------------------------------------------------------
 *		ExecInitModifyTable