| From: | didier <did447(at)gmail(dot)com> |
|---|---|
| To: | jesper(at)krogh(dot)cc |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Kevin Grittner <kgrittn(at)ymail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Bartłomiej Romański <br(at)sentia(dot)pl>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Planner performance extremely affected by an hanging transaction (20-30 times)? |
| Date: | 2013-09-24 18:03:20 |
| Message-ID: | CAJRYxuJkgePh2AntoaMCsrHQ+mdaGxw6puOVCnmOJaAyp_viyg@mail.gmail.com |
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| Lists: | pgsql-performance |
Hi
On Tue, Sep 24, 2013 at 5:01 PM, <jesper(at)krogh(dot)cc> wrote:
>
> Apparently it is waiting for locks, cant the check be make in a
> "non-blocking" way, so if it ends up waiting for a lock then it just
> assumes non-visible and moves onto the next non-blocking?
>
Not only, it's a reason but you can get the same slow down with only one
client and a bigger insert.
The issue is that a btree search for one value degenerate to a linear
search other 1000 or more tuples.
As a matter of fact you get the same slow down after a rollback until
autovacuum, and if autovacuum can't keep up...
Didier
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