Re: TOAST performance (was Re: [GENERAL] Delete Performance)

> 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.

My point is uh, um, eh, I think it is a very important point that I
should make ... um.  :-)

Seriously, how do OS's handle partial page write, especially to
directories?

Another item I was considering is that INSERT and UPDATE, because they
append to the tables, don't really cause lots of pre-page writes, while
DELETE could affect all page in a table and would require pre-page
writes on all of them.  

However, deletes are only marking the XID status of the rows. 
Unfortunately I can't think of a way of recording those new XID's in WAL
and preventing a possible failure while the XID's are written to the
page.  Can someone help me here?

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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