| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndQuadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Re: [COMMITTERS] pgsql: Remove O(N^2) performance issue with multiple SAVEPOINTs. |
| Date: | 2011-07-21 16:56:53 |
| Message-ID: | 16113.1311267413@sss.pgh.pa.us |
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Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> Instead of leaving the locks dangling to an already-destroyed resource
> owner, how about assigning all locks directly to the top-level resource
> owner in one sweep? That'd still be much better than the old way of
> recursively reassigning them up the subtransaction tree, one level at a
> time.
I haven't actually read the patch, but the reason for pushing them up
only one level at a time is that if an intermediate-level subtransaction
aborts, the locks taken by its child subtransactions have to be released
at that time. It sure sounds like this patch broke that.
regards, tom lane
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