Re: BUG #8410: out of binary heap slots - Mailing list pgsql-bugs

From Andres Freund
Subject Re: BUG #8410: out of binary heap slots
Date
Msg-id 20130830214914.GF8932@awork2.anarazel.de
Whole thread Raw
In response to Re: BUG #8410: out of binary heap slots  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: BUG #8410: out of binary heap slots
Re: BUG #8410: out of binary heap slots
List pgsql-bugs
On 2013-08-30 17:23:51 -0400, Tom Lane wrote:
> Andres Freund <andres@2ndquadrant.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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