| From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | terje(at)elde(dot)net, pgsql-bugs(at)postgresql(dot)org |
| Subject: | Re: BUG #8410: out of binary heap slots |
| Date: | 2013-08-30 21:49:14 |
| Message-ID: | 20130830214914.GF8932@awork2.anarazel.de |
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| Lists: | pgsql-bugs |
On 2013-08-30 17:23:51 -0400, Tom Lane wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> > No need, found the bug. And I think can build a testcase myself.
>
> > ExecReScanMergeAppend resets ms_initialized, but doesn't clear the
> > binaryheap. Thus no new elements fit.
>
> Sounds like a bug all right, but I'm not convinced it explains Terje's
> report. The thing this theory doesn't explain is why would Terje be
> having trouble reproducing the failure? Seems like re-running the same
> query ought to produce the same failure.
Even better explanation: The merge append is some steps below a LockRows
node, so the number of rescans might depend on the concurrency because
we'll do the EvalPlanQual dance on a concurrent row update.
Terje, do you use read committed or repeatable read/serializable?
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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