| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andrew Sullivan <andrew(at)libertyrms(dot)info> |
| Cc: | "Marc G(dot) Fournier" <scrappy(at)hub(dot)org>, Jason Watkins <jason_watkins(at)pobox(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Moving my business to PostgreSQL |
| Date: | 2002-01-29 17:12:55 |
| Message-ID: | 14936.1012324375@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Andrew Sullivan <andrew(at)libertyrms(dot)info> writes:
> If your replication is stopped for a long time, leaving the RI triggers
> on the slave sometimes prevents replication from ever catching up on
> a loaded system. I still haven't figured out why, though.
I suspect the issue has to do with the infamous "triggered data change
violation" code in 7.1. That has O(N^2) behavior if a single
transaction makes a lot of repeated updates to the same rows. Which
I think is exactly the scenario for Andrew's system when the replicator
gets behind and is trying to propagate a lot of history in one batch.
The error check and the O(N^2) behavior are both gone in 7.2.
regards, tom lane
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