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[PATCH] Add monitoring guidance to replication slot documentation

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    Venkat Venkatakrishnan<tvvraghavan@gmail.com>
    Jan 25, 2026, 10:42 AM UTC
    Hello PostgreSQL developers,
    I'm submitting a documentation improvement for Section 26.2.6 (Replication
    Slots) based on my experience as a database architect managing PostgreSQL
    high-availability environments.
    # Problem
    The current documentation warns that replication slots "can cause the
    server to retain so many WAL segments that they fill up the space allocated
    for "pgwal" and mentions "maxslotwalkeep_size" as a mitigation.
    However, it doesn't provide guidance on what DBAs should monitor to detect
    this condition before it becomes critical.
    In production environments, the database engineers need to know what
    metrics to watch, not just how to limit the problem after the fact.
    # Solution
    This patch adds specific monitoring recommendations immediately after the
    warning, including:
    - Disk space monitoring for pg_wal directory
    - Replication lag metrics from pgstatreplication (writelag, flushlag,
    replay_lag)
    - Slot status checks from pgreplicationslots (active flag, restart_lsn)
    This gives the database engineers actionable information they can use to
    set up proactive monitoring and alerting.
    # Background
    View in PostgreSQL Archives →