> On 12 Jan 2025, at 17:43, Andrey M. Borodin <x4...@yandex-team.ru> wrote: > > I attach a prototype patch.
Here's v2, now it passes all the tests with wal_debug.
Some stats. On this test
create table a as select random() from generate_series(1,1e7);
select pg_stat_reset_shared('wal'); create index on a(random ); select
pg_size_pretty(wal_bytes) from pg_stat_wal;
set wal_compression to 'lz4';
select pg_stat_reset_shared('wal'); create index on a(random ); select
pg_size_pretty(wal_bytes) from pg_stat_wal;
set wal_compression to 'pglz';
select pg_stat_reset_shared('wal'); create index on a(random ); select
pg_size_pretty(wal_bytes) from pg_stat_wal;
set wal_compression to 'zstd';
select pg_stat_reset_shared('wal'); create index on a(random ); select
pg_size_pretty(wal_bytes) from pg_stat_wal;
I observe WAL size of the index:
method HEAD patched
pglz 193 MB 193 MB
lz4 160 MB 132 MB
zstd 125 MB 97 MB
So, for lz4 and zstd this seems to be a significant reduction.
I'm planning to work on improving the patch quality.
Thanks!
Best regards, Andrey Borodin.
v2-0001-Compress-big-WAL-records.patch
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