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