Re: TOAST performance (was Re: [GENERAL] Delete Performance) - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: TOAST performance (was Re: [GENERAL] Delete Performance)
Date
Msg-id 200111220011.fAM0B8S23813@candle.pha.pa.us
Whole thread Raw
In response to Re: TOAST performance (was Re: [GENERAL] Delete Performance)  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: TOAST performance (was Re: [GENERAL] Delete Performance)
List pgsql-hackers
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Could we add code to detect a partial write when we recover from one
> > using WAL so we can know if these partial writes are ever
> > happening?
> 
> What's your point?  It clearly *can* happen during power-failure
> scenarios.  All the monitoring in the world won't disprove that.

What bothers me about this is that we have the original page with the
old data.  It would be nice if we could write the new page in a
different location, make the new page active and recycle the old page at
some later time.

We are storing the pre-page image in WAL, but it seems like a waste
because we already have a pre-image.  It is just that we are overwriting
it.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026
 


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