Enabling this forces all parse and plan trees to be passed through outfuncs.c/readfuncs.c, to facilitate catching errors and omissions in those modules.
At a glance
| Property | Value |
|---|---|
| Parameter | debug_write_read_parse_plan_trees |
| Category | Developer Options |
| Default | off |
| Value type | boolean (on/off) |
| Change scope | Per-session (SET) |
| Available in | PostgreSQL 18, 19 (added in 18) |
What it does
Enabling this forces all parse and plan trees to be passed through outfuncs.c/readfuncs.c, to facilitate catching errors and omissions in those modules. The default is off.
This parameter is only available when DEBUG_NODE_TESTS_ENABLED was defined at compile time (which happens automatically when using the configure option –enable-cassert).
(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 debug_write_read_parse_plan_trees; or SELECT name, setting, unit, context, source FROM pg_settings WHERE name = 'debug_write_read_parse_plan_trees';.
Tuning guidance
This is a developer and debugging aid, not a performance knob. Leave it at the default in production; enable it only temporarily, on a non-production or carefully controlled system, while diagnosing a specific problem. Several options in this group add overhead, generate large volumes of log output, or can damage data if misused — turn them off again as soon as the investigation is done.
Reference
PostgreSQL documentation — debug_write_read_parse_plan_trees.