Bruce Momjian <br...@momjian.us> writes: > On Fri, Mar 9, 2012 at 04:36:08PM -0800, David E. Wheeler wrote: >> A <type>bigint</type> key is displayed with its >> high-order half in the <structfield>classid</> column, its low-order >> half >> in the <structfield>objid</> column, and <structfield>objsubid</> equal >> ! to 1. The original <type>bigint</type> value can be reassembled with the >> ! expression <literal>(classid::int::bit(64) << 32 | >> ! objid::int::bit(64))::bigint</literal>. Integer keys are displayed with >> the >> ! first key in the >> <structfield>classid</> column, the second key in the >> <structfield>objid</> >> column, and <structfield>objsubid</> equal to 2. The actual meaning of >> the keys is up to the user. Advisory locks are local to each database,
> Thanks, applied. This formula is not actually correct, as you'd soon find out if you experimented with values with the high-order bit of the low-order word set. (Hint: sign extension.) The correct formula is both simpler and far more efficient: (classid::int8 << 32) | objid::int8 This works because oidtoi8 correctly treats the OID value as unsigned. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers