On Fri, Sep 5, 2014 at 7:45 PM, Peter Geoghegan <p...@heroku.com> wrote: > Attached additional patches are intended to be applied on top off most > of the patches posted on September 2nd [1].
I attach another amendment/delta patch, intended to be applied on top of what was posted yesterday. I neglected to remove some abort logic that was previously only justified by the lack of opportunistic "memcmp() == 0" comparisons in all instances, rather than just with abbreviated keys. -- Peter Geoghegan
From c60b07dda3e81e1fc9a2e95c386faf1fccfe8f04 Mon Sep 17 00:00:00 2001 From: Peter Geoghegan <p...@heroku.com> Date: Sat, 6 Sep 2014 14:56:37 -0700 Subject: [PATCH 8/8] Remove obsolete abort logic Remove some abort logic that was previously only justified by the lack of opportunistic "memcmp() == 0" comparisons in all instances, rather than just with abbreviated keys. That justification no longer stands. --- src/backend/utils/adt/varlena.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c index 6aa3eaa..db4eae1 100644 --- a/src/backend/utils/adt/varlena.c +++ b/src/backend/utils/adt/varlena.c @@ -2295,15 +2295,6 @@ bttext_abbrev_abort(int memtupcount, double rowhint, SortSupport ssup) norm_key_card = key_distinct / (double) memtupcount; /* - * If this is a very low cardinality set generally, that is reason enough - * to favor our strategy, since many comparisons can be resolved with - * inexpensive memcmp() tie-breakers, even though abbreviated keys are of - * marginal utility. - */ - if (norm_key_card < 0.05) - return false; - - /* * Abort abbreviation strategy. * * The worst case, where all abbreviated keys are identical while all -- 1.9.1
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