On 20/04/12 09:39, Condor wrote:
> Hello,
>
> when I read binary replication tutorial
> (http://wiki.postgresql.org/wiki/Binary_Replication_Tutorial) I see on
> Hot Standby: Hot Standby is identical to Warm Standby, except that the
> Standby is available to run read-only queries.
> I setup hot standby server described in tutorial and it's working fine,
> no problem with that.
> I have a problem when I try to start a script that
> should read whole table, error message from php is:
> PHP Warning: pg_query(): Query failed: ERROR: canceling statement due to
> conflict with recovery
> When data is fetched it's saved into a file after some modifications.
> This script is work a 30-40 min until all data is parsed. Well, I think
> problem is started when master server send new wal file to slave, but
> how I can resolve that problem ?
Your master database is being updated all the time and your slave is
supposed to be a perfect copy, including deleted/updated rows being no
longer visible. So - when you run a query it might need to do one of two
things:
1. Pause replication
2. Cancel the query
At some point PostgreSQL switches from doing #1 to doing #2 (otherwise
you could get so far behind the replica could never catch up). You can
control how long before it switches:
http://www.postgresql.org/docs/9.1/static/hot-standby.html#HOT-STANDBY-CONFLICT
--
Richard Huxton
Archonet Ltd
