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Support hashed aggregation with grouping sets.

author Andrew Gierth <rhodiumtoad@postgresql.org>

2017年3月27日 03:20:54 +0000 (04:20 +0100)

committer Andrew Gierth <rhodiumtoad@postgresql.org>

2017年3月27日 03:20:54 +0000 (04:20 +0100)

commit b5635948ab165b6070e7d05d111f966e07570d81

tree 9e8581fa3530ea777b14ce4900ba7cea106e3450 tree

parent f0a6046bcb15c2fe48384ef547df2bfb5d7f0a89 commit | diff

Support hashed aggregation with grouping sets.

This extends the Aggregate node with two new features: HashAggregate
can now run multiple hashtables concurrently, and a new strategy
MixedAggregate populates hashtables while doing sorted grouping.

The planner will now attempt to save as many sorts as possible when
planning grouping sets queries, while not exceeding work_mem for the
estimated combined sizes of all hashtables used. No SQL-level changes
are required. There should be no user-visible impact other than the
new EXPLAIN output and possible changes to result ordering when ORDER
BY was not used (which affected a few regression tests). The
enable_hashagg option is respected.

Author: Andrew Gierth
Reviewers: Mark Dilger, Andres Freund
Discussion: https://postgr.es/m/87vatszyhj.fsf@news-spur.riddles.org.uk

22 files changed:

contrib/postgres_fdw/expected/postgres_fdw.out diff | blob | blame | history

src/backend/commands/explain.c diff | blob | blame | history

src/backend/executor/nodeAgg.c diff | blob | blame | history

src/backend/lib/Makefile diff | blob | blame | history

src/backend/lib/knapsack.c [new file with mode: 0644] blob

src/backend/nodes/bitmapset.c diff | blob | blame | history

src/backend/nodes/outfuncs.c diff | blob | blame | history

src/backend/optimizer/path/costsize.c diff | blob | blame | history

src/backend/optimizer/plan/createplan.c diff | blob | blame | history

src/backend/optimizer/plan/planner.c diff | blob | blame | history

src/backend/optimizer/util/pathnode.c diff | blob | blame | history