Re: Microoptimization of Bitmapset usage in postgres_fdw

From: Nathan Bossart <bossartn(at)amazon(dot)com>
To: pgsql-hackers(at)lists(dot)postgresql(dot)org
Cc: Daniel Gustafsson <daniel(at)yesql(dot)se>
Subject: Re: Microoptimization of Bitmapset usage in postgres_fdw
Date: 2018-06-14 14:56:14
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The following review has been posted through the commitfest application:
make installcheck-world: not tested
Implements feature: not tested
Spec compliant: not tested
Documentation: not tested


The v2 patches look good to me. However, I found a couple other
places where we might be able to use this micro-optimization.

1) dependencies_clauselist_selectivity() in dependencies.c

* If there's not at least two distinct attnums then reject the whole list
* of clauses. We must return 1.0 so the calling function's selectivity is
* unaffected.
if (bms_num_members(clauses_attnums) < 2)
return 1.0;

2) BuildRelationExtStatistics() in extended_stats.c.

/* check allowed number of dimensions */
Assert(bms_num_members(stat->columns) >= 2 &&
bms_num_members(stat->columns) <= STATS_MAX_DIMENSIONS);


The new status of this patch is: Waiting on Author

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