Wiki / Statistics & Metrics / pg_stat_replication
pg_stat_replication.write_lag
Time elapsed between flushing recent WAL locally and receiving notification that this standby server has written it (but not yet flushed it or applied it). This can be used to gauge the delay that synchronous_commit level remote_write incurred while…
Reading PostgreSQL 18.6.
Description
Time elapsed between flushing recent WAL locally and receiving notification that this standby server has written it (but not yet flushed it or applied it). This can be used to gauge the delay that synchronous_commit level remote_write incurred while committing if this server was configured as a synchronous standby.
- View
- pg_stat_replication
- Field
- write_lag
- SQL type
- interval
- Units named in the field definition
- Not specified
- Reset observation
- No stats_reset field is documented for this view
Usage
SELECT write_lag FROM pg_catalog.pg_stat_replication;View semantics
The pg_stat_replication view will contain one row per WAL sender process, showing statistics about replication to that sender's connected standby server. Only directly connected standbys are listed; no information is available about downstream standby servers.
Collection and reset context
Read the same-version statistics collection and view documentation below for reset scope and visibility. No per-field reset rule is inferred from the field name.
Inspect this field
Example query; no execution result or measured value is asserted.
SELECT write_lag FROM pg_catalog.pg_stat_replication;Related entries
Documentation and source
Source build
- Version
- 18.6
- Build
- https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2
- Source fingerprint
555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f
Compare versions
PostgreSQL 17 → 18: unchanged.
Compares recorded interfaces and attributes. Source fingerprints and build metadata are excluded; an absent sample is not proof of the introduction or removal release.
Related entries
pg_stat_replication.application_namepg_stat_replication.backend_startpg_stat_replication.backend_xminpg_stat_replication.client_addrpg_stat_replication.client_hostnamepg_stat_replication.client_portpg_stat_replication.flush_lagpg_stat_replication.flush_lsnpg_stat_replication.pidpg_stat_replication.replay_lagpg_stat_replication.replay_lsnpg_stat_replication.reply_time
Export JSON · Back to Statistics & Metrics · Recorded in PostgreSQL 10 through 20; the first sample is not necessarily its introduction.