| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: ALTER TABLE SET STATISTICS requires AccessExclusiveLock |
| Date: | 2010-07-17 07:55:37 |
| Message-ID: | 1279353337.1735.50151.camel@ebony |
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| Thread: | |
| Lists: | pgsql-hackers |
On Fri, 2010-07-16 at 23:03 +0200, Andres Freund wrote:
> Sure its not that bad, but at least it needs to get documented imho.
> Likely others should chime in here ;-)
Don't understand you. This is a clear bug in join removal, test case
attached, a minor rework of your original test case.
> What could the join removal path (and similar places) *possibly* do
> against such a case? Without stopping to use SnapshotNow I dont see
> any way :-(
The bug is caused by allowing join removal to work in serializable
transactions. The fix for 9.0 is easy and clear: disallow join removal
when planning a query as the second or subsequent query in a
serializable transaction.
A wider fix might be worth doing for 9.1, not sure.
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Training and Services
| Attachment | Content-Type | Size |
|---|---|---|
| join_removal_serializable_bug.testcase | text/plain | 466 bytes |
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