From ea69a0dead5128c421140dc53fac165ba4af8520 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Mon, 3 Apr 2017 23:46:33 -0400 Subject: Expand hash indexes more gradually. Since hash indexes typically have very few overflow pages, adding a new splitpoint essentially doubles the on-disk size of the index, which can lead to large and abrupt increases in disk usage (and perhaps long delays on occasion). To mitigate this problem to some degree, divide larger splitpoints into four equal phases. This means that, for example, instead of growing from 4GB to 8GB all at once, a hash index will now grow from 4GB to 5GB to 6GB to 7GB to 8GB, which is perhaps still not as smooth as we'd like but certainly an improvement. This changes the on-disk format of the metapage, so bump HASH_VERSION from 2 to 3. This will force a REINDEX of all existing hash indexes, but that's probably a good idea anyway. First, hash indexes from pre-10 versions of PostgreSQL could easily be corrupted, and we don't want to confuse corruption carried over from an older release with any corruption caused despite the new write-ahead logging in v10. Second, it will let us remove some backward-compatibility code added by commit 293e24e507838733aba4748b514536af2d39d7f2. Mithun Cy, reviewed by Amit Kapila, Jesper Pedersen and me. Regression test outputs updated by me. Discussion: http://postgr.es/m/CAD__OuhG6F1gQLCgMQNnMNgoCvOLQZz9zKYJQNYvYmmJoM42gA@mail.gmail.com Discussion: http://postgr.es/m/CA+TgmoYty0jCf-pa+m+vYUJ716+AxM7nv_syvyanyf5O-L_i2A@mail.gmail.com --- contrib/pgstattuple/expected/pgstattuple.out | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'contrib/pgstattuple') diff --git a/contrib/pgstattuple/expected/pgstattuple.out b/contrib/pgstattuple/expected/pgstattuple.out index 2c3515b4eff..86a7c78fbb5 100644 --- a/contrib/pgstattuple/expected/pgstattuple.out +++ b/contrib/pgstattuple/expected/pgstattuple.out @@ -134,7 +134,7 @@ create index test_hashidx on test using hash (b); select * from pgstathashindex('test_hashidx'); version | bucket_pages | overflow_pages | bitmap_pages | zero_pages | live_items | dead_items | free_percent ---------+--------------+----------------+--------------+------------+------------+------------+-------------- - 2 | 4 | 0 | 1 | 0 | 0 | 0 | 100 + 3 | 4 | 0 | 1 | 0 | 0 | 0 | 100 (1 row) -- these should error with the wrong type @@ -235,7 +235,7 @@ select pgstatindex('test_partition_idx'); select pgstathashindex('test_partition_hash_idx'); pgstathashindex --------------------- - (2,8,0,1,0,0,0,100) + (3,8,0,1,0,0,0,100) (1 row) drop table test_partitioned; -- cgit v1.2.3