Re: [HACKERS] Replication slots and isolation levels - Mailing list pgsql-admin

From Vladimir Borodin
Subject Re: [HACKERS] Replication slots and isolation levels
Date
Msg-id 088B276D-4073-4582-82D4-08F50E43B426@simply.name
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In response to Re: [HACKERS] Replication slots and isolation levels  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: [HACKERS] Replication slots and isolation levels  (Michael Paquier <michael.paquier@gmail.com>)
Re: [HACKERS] Replication slots and isolation levels  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-admin

30 окт. 2015 г., в 14:30, Robert Haas <robertmhaas@gmail.com> написал(а):

On Thu, Oct 29, 2015 at 3:29 PM, Oleksii Kliukin <alexk@hintbits.com> wrote:
Could it be a consequence of how REPEATABLE READ transactions handle
snapshots? With REPEATABLE READ the snapshot is acquired only once at the
beginning of a transaction; a READ COMMITTED transaction re-evaluates its
snapshot with each new command.

I bet that's exactly it.

I still don’t fully understand why is it so (the problem occurs while running only one SELECT-statement in READ COMMITED so only one snapshot is taken), but if is expected behavior shouldn’t the documentation mention that using READ COMMITED (which is the default) you may still get conflicts with recovery while using replication slots?


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Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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May the force be with you…

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