max_pred_locks_per_page — PostgreSQL configuration parameter

This controls how many rows on a single page can be predicate-locked before the lock is promoted to covering the whole page.

At a glance

What it does

This controls how many rows on a single page can be predicate-locked before the lock is promoted to covering the whole page. The default is 2. This parameter can only be set in the postgresql.conf file or on the server command line.

(Description quoted from the official PostgreSQL documentation.)

How to apply a change

Set it in postgresql.conf (or with ALTER SYSTEM) and reload with SELECT pg_reload_conf(); or pg_ctl reload — no restart needed.

Inspect the current value and source with SHOW max_pred_locks_per_page; or SELECT name, setting, unit, context, source FROM pg_settings WHERE name = 'max_pred_locks_per_page';.

Tuning guidance

This parameter is rarely a performance lever. Leave it at the default unless you have a specific, documented reason to change it, change it on one session or one role/database first, and confirm the effect with pg_settings and your own measurements before rolling it out cluster-wide.

Reference

PostgreSQL documentation — max_pred_locks_per_page.