Horton

Re: CLUSTER sort on abbreviated expressions is broken

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: John Naylor <john.naylor@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-04-03T23:33:28Z
Lists: pgsql-hackers 
On Mon, Apr 4, 2022 at 11:12 AM Peter Geoghegan <pg@bowt.ie> wrote:
> We will need a backpatchable fix, since Thomas' recent fix (commit
> cc58eecc5d75a9329a6d49a25a6499aea7ee6fd6) only targeted the master
> branch.

I probably should have made it clearer in the commit message,
cc58eecc5 doesn't fix this problem in the master branch.  It only
fixes the code that incorrectly assumed that datum1 was always
available.  Now it skips the optimised path, and falls back to the
slow path, that still has *this* bug, and the test upthread still
fails.  I wrote about this separately because it's clearly independent
and I didn't want it to be mistaken for an open item for 15.

Commits

  1. Fix CLUSTER tuplesorts on abbreviated expressions.

  2. Fix tuplesort optimization for CLUSTER-on-expression.