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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2016-06-16 13:47:20 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2016-06-16 13:47:20 -0400 |
| commit | 75be66464cb1bffa1e5757907b9a04ad5afc7859 (patch) | |
| tree | 71d51f8b6e3ba127480cf6165b4b2c165c2fea0f /src/backend/utils/misc/guc.c | |
| parent | 3b5a2a8856b810ed354fb6dbb7df8d7325ece82f (diff) | |
| download | postgresql-75be66464cb1bffa1e5757907b9a04ad5afc7859.tar.gz postgresql-75be66464cb1bffa1e5757907b9a04ad5afc7859.zip | |
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: <17170.1465830165@sss.pgh.pa.us>
Diffstat (limited to 'src/backend/utils/misc/guc.c')
| -rw-r--r-- | src/backend/utils/misc/guc.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 9b02111a834..60148b871b3 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -2748,6 +2748,17 @@ static struct config_int ConfigureNamesInt[] = }, { + {"min_parallel_relation_size", PGC_USERSET, QUERY_TUNING_COST, + gettext_noop("Sets the minimum size of relations to be considered for parallel scan."), + NULL, + GUC_UNIT_BLOCKS, + }, + &min_parallel_relation_size, + 1024, 0, INT_MAX / 3, + NULL, NULL, NULL + }, + + { /* Can't be set in postgresql.conf */ {"server_version_num", PGC_INTERNAL, PRESET_OPTIONS, gettext_noop("Shows the server version as an integer."), |