Ilegal type cast in _hash_doinsert()

There seems to be some base bug in _hash_doinsert().
+ * XXX this is useless code if we are only storing hash keys.

+ */

+ if (itemsz > HashMaxItemSize((Page) metap))

+ ereport(ERROR,

+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),

+ errmsg("index row size %zu exceeds hash maximum %zu",

+ itemsz, HashMaxItemSize((Page) metap)),

+ errhint("Values larger than a buffer page cannot be
indexed.")));

"metap" (HashMetaPage) is not a Page (they the entirely different
structure), so above casting is not legal. Added a patch to correct same by
passing actual Page which stores "HashMetaPage".

--
Thanks and Regards
Mithun C Y
EnterpriseDB: http://www.enterprisedb.com