Re: Piggybacking vacuum I/O - Mailing list pgsql-hackers

From Heikki Linnakangas
Subject Re: Piggybacking vacuum I/O
Date
Msg-id 45B9CA82.8040601@enterprisedb.com
Whole thread Raw
In response to Re: Piggybacking vacuum I/O  (Bruce Momjian <bruce@momjian.us>)
Responses Re: Piggybacking vacuum I/O  (Alvaro Herrera <alvherre@commandprompt.com>)
Re: Piggybacking vacuum I/O  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
I'd like to see still more evidence that it's a problem before we start 
changing that piece of code. It has served us well for years.

Bruce Momjian wrote:
> Is there a TODO here?
> 
> ---------------------------------------------------------------------------
> 
> Heikki Linnakangas wrote:
>> Pavan Deolasee wrote:
>>> Another simpler solution for VACUUM would be to read the entire CLOG file
>>> in local memory. Most of the transaction status queries can be satisfied
>>> from
>>> this local copy and the normal CLOG is consulted only when the status is
>>> unknown (TRANSACTION_STATUS_IN_PROGRESS)
>> The clog is only for finished (committed/aborted/crashed) transactions.
>> If a transaction is in progress, the clog is never consulted. Anyway,
>> that'd only be reasonable for vacuums, and I'm actually more worried if
>> we had normal backends thrashing the clog buffers.


--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com


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