I use PG v15.4 with TimescaleDB v2.16.0 self-hosted on prem.
I am looking at pg_wal directory and I see individual WAL file is 16 MB in size. I am reading (free to download) book “PostgreSQL 14 Internals” where it is written: “On disk, the WAL is stored in the PGDATA/pg_wal directory as separate files, or segments. Their size is shown by the read-only 16MB “wal_segment_size” parameter. For high-load systems, it makes sense to increase the segment size since it may reduce the overhead.”
Like I understand when 16MB WAL file is filled new WAL file must be created. Regularly requesting operating system to create new file takes some time. In high-load this may not be negligible, so increasing WAL size may benefit of writing transaction faster.
TimescaleDB systems are by definition high-load systems.
QUESTIONS:
- What is recommended wal_segment_size parameter for TimescaleDB?
- Does someone has some experience, does increasing parameter to 32MB (or more) increase performance?
- What are disadvantages of having larger WAL log segments?
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