Re: Re: [COMMITTERS] pgsql: Augment WAL records for btree delete with GetOldestXmin() to
Simon Riggs <simon@2ndquadrant.com>
From: Simon Riggs <simon@2ndQuadrant.com>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@postgresql.org
Date: 2010-01-31T21:56:06Z
Lists: pgsql-hackers
On Sun, 2010-01-31 at 23:43 +0200, Heikki Linnakangas wrote: > IIRC it was Greg Stark who suggested last time this was discussed that > we could calculate the exact value for latestRemovedXid in the > standby. When replaying the deletion record, the standby could look at > all the heap tuples whose index pointers are being removed, to see > which one was newest. That can be pretty expensive, involving random > I/O, but it gives an exact value, and doesn't stress the master at > all. And we could skip it if there's no potentially conflicting > read-only queries running. > > That seems like the most user-friendly approach to me. Even though > random I/O is expensive, surely it's better than killing queries. Best solution, no time to do it. Should I revoke this change? -- Simon Riggs www.2ndQuadrant.com