Re: BUG #8410: out of binary heap slots

Andres Freund <andres@2ndquadrant.com> writes:
> On 2013-08-30 23:05:25 +0200, Andres Freund wrote:
>> ExecReScanMergeAppend resets ms_initialized, but doesn't clear the
>> binaryheap. Thus no new elements fit.

> Ok, patch for that attached.

I think the comments need a bit of copy-editing, but looks good otherwise.
Will fix and commit.

> Should we add
> SELECT (SELECT g.i FROM ((SELECT random()::int ORDER BY 1 OFFSET 0) UNION ALL (SELECT random()::int ORDER BY 1 OFFSET
0))f(i) ORDER BY f.i LIMIT 1) FROM generate_series(1, 10) g(i); 
> as a regression test? I slightly on the "no" side...

Not sure.  It's pretty disturbing that this wasn't caught earlier;
it seems to me that means there's no regression coverage that hits
ExecReScanMergeAppend.  However, I don't much like this specific test case
because it seems like hitting the bug could depend on what series of
random values you get.

            regards, tom lane