Function CatalogCacheComputeTupleHashValue

src/backend/utils/cache/catcache.c:319–367

* CatalogCacheComputeTupleHashValue * * Compute the hash value associated with a given tuple to be cached */

 * Compute the hash value associated with a given tuple to be cached
 */
static uint32
CatalogCacheComputeTupleHashValue(CatCache *cache, int nkeys, HeapTuple tuple)
{
	Datum		v1 = 0,
				v2 = 0,
				v3 = 0,
				v4 = 0;
	bool		isNull = false;
	int		   *cc_keyno = cache->cc_keyno;
	TupleDesc	cc_tupdesc = cache->cc_tupdesc;

	/* Now extract key fields from tuple, insert into scankey */
	switch (nkeys)
	{
		case 4:
			v4 = fastgetattr(tuple,
							 cc_keyno[3],
							 cc_tupdesc,
							 &isNull);
			Assert(!isNull);
			/* FALLTHROUGH */
		case 3:
			v3 = fastgetattr(tuple,
							 cc_keyno[2],
							 cc_tupdesc,
							 &isNull);
			Assert(!isNull);
			/* FALLTHROUGH */
		case 2:
			v2 = fastgetattr(tuple,
							 cc_keyno[1],
							 cc_tupdesc,
							 &isNull);
			Assert(!isNull);
			/* FALLTHROUGH */
		case 1:
			v1 = fastgetattr(tuple,
							 cc_keyno[0],
							 cc_tupdesc,
							 &isNull);
			Assert(!isNull);
			break;
		default:
			elog(FATAL, "wrong number of hash keys: %d", nkeys);
			break;
	}

	return CatalogCacheComputeHashValue(cache, nkeys, v1, v2, v3, v4);
}

/*
 *		CatalogCacheCompareTuple