postgresql.replication.replay_lsn_delay

Replication replay LSN delay

Dimensions:None

Available on:Native (1)

Datadog (1)

Interface Metrics (2)

Native

replay_lsn

replay_lsn statistic from pg_stat_replication

Dimensions:None

Datadog

postgresql.replication.replay_lsn_delay

The delay in bytes between the current WAL position and the last location replayed by the standby server

Dimensions:None

Sources

replay_lsngithub.com

postgresql.replication.replay_lsn_delaygithub.com

Technical Annotations (18)

Configuration Parameters (6)

wal_keep_segmentsrecommended: increase from default

number of WAL segments to retain in pg_xlog directory

max_wal_sendersrecommended: increase from default

maximum concurrent WAL sender processes allowed

archive_moderecommended: on

enable WAL archiving to preserve segments

archive_commandrecommended: configured to alternate path

command to archive WAL files to backup location

max_standby_streaming_delayrecommended: 30s

maximum time standby waits before canceling queries during replay

hot_standby_feedbackrecommended: on

prevents query cancellations on standby by informing primary

CLI Commands (6)

SELECT client_addr, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, pg_wal_lsn_diff(sent_lsn, replay_lsn) AS lag_bytes FROM pg_stat_replication;

monitoring

SELECT now() - pg_last_xact_replay_timestamp() AS replication_lag;monitoring

ALTER SYSTEM SET max_wal_senders = 10;remediation

ALTER SYSTEM SET wal_keep_segments = 64;remediation

ALTER SYSTEM SET max_standby_streaming_delay = '30s';remediation

ALTER SYSTEM SET hot_standby_feedback = on;remediation

Technical References (6)

WALcomponentWrite-Ahead Loggingconceptpg_xlogfile pathcheckpointconceptpg_stat_replicationcomponentstreaming replicationconcept

Related Insights (3)

WAL segment deletion causes replication lag and requires replica rebuildcritical

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Replication lag causing stale reads on standbywarning

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Replication lag causes stale reads on replicaswarning

Streaming replication lag between primary and replica nodes increases, causing replicas to serve stale data. High lag indicates replica cannot keep up with primary write volume, network issues, or resource constraints on replica.

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