Horton

Re: tuplesort memory usage: grow_memtuples

Peter Geoghegan <peter@2ndquadrant.com>

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From: Peter Geoghegan <peter@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Simon Riggs <simon@2ndquadrant.com>, Jeff Janes <jeff.janes@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Greg S <stark@mit.edu>
Date: 2012-11-15T19:13:58Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Incorporate a couple of recent tuplesort.c improvements into tuplestore.c.

On 15 November 2012 18:13, Robert Haas <robertmhaas@gmail.com> wrote:
> Ah, yeah.  I wondered in passing about that but forgot to follow up on
> it.  The problem specifically is that the intermediate result
> memtupsize * newmemtuples might overflow.  I believe that the old
> memtupsize can never be more than 2^26 bytes, because the allocation
> limit is 1GB and each SortTuple is 16 bytes.

Do you mean the intermediate result of memtupsize * allowedMem? Oh,
yeah, that could overflow rather easily on a platform where long is
only 32-bit. We're multiplying the entire current allocation size of
the array by the maximum length. I guess the fact that you didn't spot
it made me overconfident. :-)

-- 
Peter Geoghegan       http://www.2ndQuadrant.com/
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