Horton

Re: Restricting maximum keep segments by repslots

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

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From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Petr Jelinek <petr.jelinek@2ndquadrant.com>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, pgsql-hackers@postgresql.org
Date: 2017-03-01T17:17:43Z
Lists: pgsql-hackers 
On 2/27/17 23:27, Petr Jelinek wrote:
>>> WARNING:  restart LSN of replication slots is ignored by checkpoint
>>> DETAIL:  Some replication slots lose required WAL segnents to continue.
> However this is dangerous as logical replication slot does not consider
> it error when too old LSN is requested so we'd continue replication,
> hiding data loss.

In general, we would need a much more evident and strict way to discover
when this condition is hit.  Like a "full" column in
pg_stat_replication_slot, and refusing connections to the slot until it
is cleared.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Save slot's restart_lsn when invalidated due to size

  2. Fix checkpoint signalling

  3. Check slot->restart_lsn validity in a few more places

  4. Allow users to limit storage reserved by replication slots

  5. Remove header noise from test_decoding test

  6. Rework WAL-reading supporting structs

  7. Flip argument order in XLogSegNoOffsetToRecPtr