From 453957c7e2d39134b3a43c878f27f1748dde7c9f Mon Sep 17 00:00:00 2001 From: Laurenz Albe Date: Tue, 21 Jul 2026 21:02:59 +0200 Subject: [PATCH v3] Properly document pg_stat_activity.backend_type The documentation of pg_stat_activity should list all possible values for the backend type, but the list was inaccurate and incomplete. Since the complete list is pretty long, turn it into an alphabetically sorted itemized list and add a description for each type. Author: Laurenz Albe Reviewed-By: Michael Paquier Reviewed-By: Fujii Masao Discussion: https://postgr.es/m/5e94c0196084f648ae6a00107125494f5804318a.camel@cybertec.at --- doc/src/sgml/monitoring.sgml | 165 ++++++++++++++++++++++++++++++++--- 1 file changed, 155 insertions(+), 10 deletions(-) diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index d1a20d001e9..12ecba6e275 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -1057,16 +1057,161 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser backend_type text - Type of current backend. Possible types are - autovacuum launcher, autovacuum worker, - logical replication launcher, - logical replication worker, - parallel worker, background writer, - client backend, checkpointer, - archiver, standalone backend, - startup, walreceiver, - walsender, walwriter and - walsummarizer. + Type of current backend. Possible types are: + + + + archiver: The WAL archiver, active when + is on. + + + + + autovacuum launcher: The background process that + launches autovacuum workers, active when + is on. + + + + + autovacuum worker: A background process running + VACUUM or ANALYZE on a single + table. + + + + + background writer: The background process that + makes sure that there are enough clean buffers in shared buffers. + + + + + checkpointer: The background process that + performs checkpoints + regularly. + + + + + client backend: The server process performing + work for a regular database connection. + + + + + datachecksums launcher: The background process + that launches data checksum workers. + + + + + datachecksums worker: A background process that + calculates data checksums for all pages in one database. + + + + + io worker: A background process performing + asynchronous I/O, active when is set + to worker. + + + + + logical replication launcher: The background + process that launches logical replication worker processes for + subscriptions. + + + + + logical replication apply worker: A background + process that applies data modifications on a logical subscriber. + + + + + logical replication parallel worker: A background + process that applies data modifications on a logical subscriber + for a subscription with streaming = parallel. + + + + + logical replication sequencesync worker: A + background process that replicates sequence data on a logical + subscriber. + + + + + logical replication tablesync worker: A + background process that copies table data on a logical subscriber + for a subscription with copy_data = true. + + + + + parallel worker: A background process that helps + a backend process to perform operations in parallel. + + + + + REPACK decoding worker: A background process that + decodes WAL for REPACK (CONCURRENTLY). + + + + + slotsync worker: The background process that + synchronizes logical replication slots on a streaming replication + standby server, active when + is set to on. + + + + + standalone backend: The backend process when + PostgreSQL was started in + . + + + + + startup: The background process that replays WAL + during crash recovery, archive recovery or streaming replication. + + + + + walreceiver: The background process that receives + WAL records from a WAL sender, active in streaming replication + standby mode. + + + + + walsender: A background process that sends WAL + records to receivers (during streaming replication) or decodes WAL + and sends the decoded information (during logical replication). + + + + + walsummarizer: The background process that + creates summaries from WAL for use with incremental backup, active + when is on. + + + + + walwriter: The background process that persists + WAL records from WAL buffers to disk. + + + In addition, background workers registered by extensions may have additional types. -- 2.55.0