Reports the size of a WAL disk block.
At a glance
| Property | Value |
|---|---|
| Parameter | wal_block_size |
| Category | Preset Options |
| Default | 8192 |
| Value type | integer |
| Change scope | Per-session (SET) |
| Available in | PostgreSQL 12, 13, 14, 15, 16, 17, 18, 19 (added in 12) |
What it does
Reports the size of a WAL disk block. It is determined by the value of XLOG_BLCKSZ when building the server. The default value is 8192 bytes.
(Description quoted from the official PostgreSQL documentation.)
How to apply a change
Can be set per session with SET, per role/database with ALTER ROLE/DATABASE ... SET, or globally in postgresql.conf.
Inspect the current value and source with SHOW wal_block_size; or SELECT name, setting, unit, context, source FROM pg_settings WHERE name = 'wal_block_size';.
Tuning guidance
This is a preset, read-only parameter: it reports a value fixed when PostgreSQL was built or the cluster was initialized, and cannot be tuned at runtime. Read it to verify the server’s build or cluster configuration (for example when matching a replica or debugging a compatibility issue); there is no setting to adjust.