diff options
| author | Robert Haas | 2017-02-15 18:37:24 +0000 |
|---|---|---|
| committer | Robert Haas | 2017-02-15 18:37:24 +0000 |
| commit | 51ee6f3160d2e1515ed6197594bda67eb99dc2cc (patch) | |
| tree | c711d90b31669b782f1c0a6e48cfecf1348689cd /src/test | |
| parent | 5d40286985af3ea60eda3b873ce4ee26f96505f4 (diff) | |
Replace min_parallel_relation_size with two new GUCs.
When min_parallel_relation_size was added, the only supported type
of parallel scan was a parallel sequential scan, but there are
pending patches for parallel index scan, parallel index-only scan,
and parallel bitmap heap scan. Those patches introduce two new
types of complications: first, what's relevant is not really the
total size of the relation but the portion of it that we will scan;
and second, index pages and heap pages shouldn't necessarily be
treated in exactly the same way. Typically, the number of index
pages will be quite small, but that doesn't necessarily mean that
a parallel index scan can't pay off.
Therefore, we introduce min_parallel_table_scan_size, which works
out a degree of parallelism for scans based on the number of table
pages that will be scanned (and which is therefore equivalent to
min_parallel_relation_size for parallel sequential scans) and also
min_parallel_index_scan_size which can be used to work out a degree
of parallelism based on the number of index pages that will be
scanned.
Amit Kapila and Robert Haas
Discussion: http://postgr.es/m/CAA4eK1KowGSYYVpd2qPpaPPA5R90r++QwDFbrRECTE9H_HvpOg@mail.gmail.com
Discussion: http://postgr.es/m/CAA4eK1+TnM4pXQbvn7OXqam+k_HZqb0ROZUMxOiL6DWJYCyYow@mail.gmail.com
Diffstat (limited to 'src/test')
| -rw-r--r-- | src/test/regress/expected/select_parallel.out | 2 | ||||
| -rw-r--r-- | src/test/regress/sql/select_parallel.sql | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out index 8786678f0cf..3692d4f1b81 100644 --- a/src/test/regress/expected/select_parallel.out +++ b/src/test/regress/expected/select_parallel.out @@ -9,7 +9,7 @@ begin isolation level repeatable read; -- encourage use of parallel plans set parallel_setup_cost=0; set parallel_tuple_cost=0; -set min_parallel_relation_size=0; +set min_parallel_table_scan_size=0; set max_parallel_workers_per_gather=4; explain (costs off) select count(*) from a_star; diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql index def9939d2e6..f4f9dd5ab67 100644 --- a/src/test/regress/sql/select_parallel.sql +++ b/src/test/regress/sql/select_parallel.sql @@ -12,7 +12,7 @@ begin isolation level repeatable read; -- encourage use of parallel plans set parallel_setup_cost=0; set parallel_tuple_cost=0; -set min_parallel_relation_size=0; +set min_parallel_table_scan_size=0; set max_parallel_workers_per_gather=4; explain (costs off) |