Function SearchCatCacheMiss

src/backend/utils/cache/catcache.c:1365–1493

* Search the actual catalogs, rather than the cache. * * This is kept separate from SearchCatCacheInternal() to keep the fast-path * as small as possible. To avoid that effort being undone by a helpful * compiler, try to explicitly forbid inlining. */

 * compiler, try to explicitly forbid inlining.
 */
static pg_noinline HeapTuple
SearchCatCacheMiss(CatCache *cache,
				   int nkeys,
				   uint32 hashValue,
				   Index hashIndex,
				   Datum v1,
				   Datum v2,
				   Datum v3,
				   Datum v4)
{
	ScanKeyData cur_skey[CATCACHE_MAXKEYS];
	Relation	relation;
	SysScanDesc scandesc;
	HeapTuple	ntp;
	CatCTup    *ct;
	Datum		arguments[CATCACHE_MAXKEYS];

	/* Initialize local parameter array */
	arguments[0] = v1;
	arguments[1] = v2;
	arguments[2] = v3;
	arguments[3] = v4;

	/*
	 * Ok, need to make a lookup in the relation, copy the scankey and fill
	 * out any per-call fields.
	 */
	memcpy(cur_skey, cache->cc_skey, sizeof(ScanKeyData) * nkeys);
	cur_skey[0].sk_argument = v1;
	cur_skey[1].sk_argument = v2;
	cur_skey[2].sk_argument = v3;
	cur_skey[3].sk_argument = v4;

	/*
	 * Tuple was not found in cache, so we have to try to retrieve it directly
	 * from the relation.  If found, we will add it to the cache; if not
	 * found, we will add a negative cache entry instead.
	 *
	 * NOTE: it is possible for recursive cache lookups to occur while reading
	 * the relation --- for example, due to shared-cache-inval messages being
	 * processed during table_open().  This is OK.  It's even possible for one
	 * of those lookups to find and enter the very same tuple we are trying to
	 * fetch here.  If that happens, we will enter a second copy of the tuple
	 * into the cache.  The first copy will never be referenced again, and
	 * will eventually age out of the cache, so there's no functional problem.
	 * This case is rare enough that it's not worth expending extra cycles to
	 * detect.
	 */
	relation = table_open(cache->cc_reloid, AccessShareLock);

	scandesc = systable_beginscan(relation,
								  cache->cc_indexoid,
								  IndexScanOK(cache, cur_skey),
								  NULL,
								  nkeys,
								  cur_skey);

	ct = NULL;