postgres-github.git / summary / log / commit / refs

commit    7e8aeb9e483db48500987da8981a70b491b7844c
Author:   Alexander Korotkov <akorotkov@postgresql.org>
Date:     Mon Apr 06 19:41:02 2026 +0000

    Use WAIT FOR LSN in PostgreSQL::Test::Cluster::wait_for_catchup()
    
    When the standby is passed as a PostgreSQL::Test::Cluster instance,
    use the WAIT FOR LSN command on the standby server to implement
    wait_for_catchup() for replay, write, and flush modes.  This is more
    efficient than polling pg_stat_replication on the upstream, as the
    WAIT FOR LSN command uses a latch-based wakeup mechanism.
    
    The optimization applies when:
    - The standby is passed as a Cluster object (not just a name string)
    - The mode is 'replay', 'write', or 'flush' (not 'sent')
    
    Rather than pre-checking pg_is_in_recovery() on the standby (which
    would add an extra round-trip on every call), we issue WAIT FOR LSN
    directly and handle the 'not in recovery' result as a signal to fall
    back to polling.
    
    For 'sent' mode, when the standby is passed as a string (e.g., a
    subscription name for logical replication), when the standby has been
    promoted, or when WAIT FOR LSN is interrupted by a recovery conflict,
    the function falls back to the original polling-based approach using
    pg_stat_replication on the upstream.  The recovery conflict fallback
    is necessary because some conflicts are unavoidable - for example,
    ResolveRecoveryConflictWithTablespace() kills all backends
    unconditionally, regardless of what they are doing.
    
    The recovery conflict detection matches the English error message
    "conflict with recovery", which is reliable because the test suite
    runs with LC_MESSAGES=C.
    
    Discussion: https://postgr.es/m/CABPTF7UiArgW-sXj9CNwRzUhYOQrevLzkYcgBydmX5oDes1sjg%40mail.gmail.com
    Author: Xuneng Zhou <xunengzhou@gmail.com>
    Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
    Reviewed-by: Chao Li <li.evan.chao@gmail.com>
    Reviewed-by: Alvaro Herrera <alvherre@kurilemu.de>

[parent: 834038c1f8d5]