log_statement_stats

Definition PG 18 manual

For each query, output performance statistics of the respective module to the server log. This is a crude profiling instrument, similar to the Unix getrusage() operating system facility. log_statement_stats reports total statement statistics, while the others report per-module statistics. log_statement_stats cannot be enabled together with any of the per-module options. All of these options are disabled by default. Only superusers and users with the appropriate SET privilege can change these settings.

How it works

log_statement_stats emits whole-statement resource usage for every query using a crude getrusage-style profiler. Output goes to the server log and is intended for short diagnostic sessions.

log_statement_stats reports the total statement, while parser, planner, and executor switches report individual phases. The total switch cannot be enabled together with any per-phase switch.

This is synchronous diagnostic logging rather than the cumulative statistics system. Volume and formatting make it unsuitable as routine production telemetry. Its superuser context permits an authorized session change without a server restart.

Operational considerations

Enabling or enlarging log_statement_stats without measuring collection and observation overhead.

Confusing collection semantics with a performance-control or I/O-control setting.

Assuming all statistics are immediately current inside a long transaction.

Collecting sensitive query text or identifiers without matching access and retention policy.

Workload guidance

OLAP: For a specific analytical statement, EXPLAIN (ANALYZE, BUFFERS) and cumulative views are usually more actionable than cluster-wide log_statement_stats. Scope any use and budget log volume.

OLTP: Do not enable log_statement_stats as normal OLTP tuning. Use it briefly on an isolated reproduction or one controlled session, collect the needed log, then disable it.

SMALL: Leave log_statement_stats=off. A small host is especially vulnerable to diagnostic log I/O and storage exhaustion.