From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | pgsql-committers(at)postgresql(dot)org |
Subject: | pgsql: Invent min_parallel_relation_size GUC to replace a hard-wired co |
Date: | 2016-06-16 17:47:26 |
Message-ID: | E1bDbO2-0008Hb-6W@gemulon.postgresql.org |
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Lists: | pgsql-committers |
Invent min_parallel_relation_size GUC to replace a hard-wired constant.
The main point of doing this is to allow the cutoff to be set very small,
even zero, to allow parallel-query behavior to be tested on relatively
small tables such as we typically use in the regression tests. But it
might be of use to users too. The number-of-workers scaling behavior in
create_plain_partial_paths() is pretty ad-hoc and subject to change, so
we won't expose anything about that, but the notion of not considering
parallel query at all for tables below size X seems reasonably stable.
Amit Kapila, per a suggestion from me
Discussion: <17170(dot)1465830165(at)sss(dot)pgh(dot)pa(dot)us>
Branch
------
master
Details
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http://git.postgresql.org/pg/commitdiff/75be66464cb1bffa1e5757907b9a04ad5afc7859
Modified Files
--------------
doc/src/sgml/config.sgml | 14 ++++++++++++++
src/backend/optimizer/path/allpaths.c | 15 ++++++++++-----
src/backend/utils/misc/guc.c | 11 +++++++++++
src/backend/utils/misc/postgresql.conf.sample | 1 +
src/include/optimizer/paths.h | 1 +
5 files changed, 37 insertions(+), 5 deletions(-)
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