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base repository: postgresql-cfbot/postgresql
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  • 2 commits
  • 30 files changed
  • 2 contributors

Commits on Mar 16, 2025

  1. Implement WAIT FOR command 

    WAIT FOR is to be used on standby and specifies waiting for
the specific WAL location to be replayed.  This option is useful when
the user makes some data changes on primary and needs a guarantee to see
these changes are on standby.

The queue of waiters is stored in the shared memory as an LSN-ordered pairing
heap, where the waiter with the nearest LSN stays on the top.  During
the replay of WAL, waiters whose LSNs have already been replayed are deleted
from the shared memory pairing heap and woken up by setting their latches.

WAIT FOR needs to wait without any snapshot held.  Otherwise, the snapshot
could prevent the replay of WAL records, implying a kind of self-deadlock.
This is why separate utility command seems appears to be the most robust
way to implement this functionality.  It's not possible to implement this as
a function.  Previous experience shows that stored procedures also have
limitation in this aspect.

Discussion: https://postgr.es/m/eb12f9b03851bb2583adab5df9579b4b%40postgrespro.ru
Author: Kartyshov Ivan <[email protected]>
Author: Alexander Korotkov <[email protected]>
Reviewed-by: Michael Paquier <[email protected]>
Reviewed-by: Peter Eisentraut <[email protected]>
Reviewed-by: Dilip Kumar <[email protected]>
Reviewed-by: Amit Kapila <[email protected]>
Reviewed-by: Alexander Lakhin <[email protected]>
Reviewed-by: Bharath Rupireddy <[email protected]>
Reviewed-by: Euler Taveira <[email protected]>
Reviewed-by: Heikki Linnakangas <[email protected]>
Reviewed-by: Kyotaro Horiguchi <[email protected]>
Reviewed-by: Yura Sokolov <[email protected]>
    @akorotkov
    akorotkov authored and Commitfest Bot committed Mar 16, 2025
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  2. [CF 5550] v6 - Waiting for LSN replay with WAIT FOR command 

    This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/5550

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/[email protected]
Author(s): Alexander Korotkov
    Commitfest Bot committed Mar 16, 2025
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