Re: Re: [COMMITTERS] pgsql: Augment WAL records for btree delete with GetOldestXmin() to - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: Re: [COMMITTERS] pgsql: Augment WAL records for btree delete with GetOldestXmin() to
Date
Msg-id 1264974966.13782.8948.camel@ebony
Whole thread Raw
In response to Re: Re: [COMMITTERS] pgsql: Augment WAL records for btree delete with GetOldestXmin() to  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: Re: [COMMITTERS] pgsql: Augment WAL records for btree delete with GetOldestXmin() to
List 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



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