Function find_oper_cache_entry

src/backend/parser/parse_oper.c:993–1025

* find_oper_cache_entry * * Look for a cache entry matching the given key. If found, return the * contained operator OID, else return InvalidOid. */

 * contained operator OID, else return InvalidOid.
 */
static Oid
find_oper_cache_entry(OprCacheKey *key)
{
	OprCacheEntry *oprentry;

	if (OprCacheHash == NULL)
	{
		/* First time through: initialize the hash table */
		HASHCTL		ctl;

		ctl.keysize = sizeof(OprCacheKey);
		ctl.entrysize = sizeof(OprCacheEntry);
		OprCacheHash = hash_create("Operator lookup cache", 256,
								   &ctl, HASH_ELEM | HASH_BLOBS);

		/* Arrange to flush cache on pg_operator and pg_cast changes */
		CacheRegisterSyscacheCallback(OPERNAMENSP,
									  InvalidateOprCacheCallBack,
									  (Datum) 0);
		CacheRegisterSyscacheCallback(CASTSOURCETARGET,
									  InvalidateOprCacheCallBack,
									  (Datum) 0);
	}

	/* Look for an existing entry */
	oprentry = (OprCacheEntry *) hash_search(OprCacheHash,
											 (void *) key,
											 HASH_FIND, NULL);
	if (oprentry == NULL)
		return InvalidOid;

	return oprentry->opr_oid;
}

/*
 * make_oper_cache_entry