Re: pgbench -i spends all its time doing CHECKPOINT - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: pgbench -i spends all its time doing CHECKPOINT
Date
Msg-id 200201061801.g06I1fb24803@candle.pha.pa.us
Whole thread Raw
In response to Re: pgbench -i spends all its time doing CHECKPOINT  (Tatsuo Ishii <t-ishii@sra.co.jp>)
Responses Re: pgbench -i spends all its time doing CHECKPOINT  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tatsuo Ishii wrote:
> > Could we remove lines 552-560 of pgbench.c?  The behavior that guarded
> > against is long gone, and forcing a checkpoint every few thousand tuples
> > seems to be putting a huge crimp in the speed of pgbench -i ...
> 
> Yup. Maybe we could ifdef'ed out until we implement true UNDO...

I think we should just remove it.  The idea that we are going to do UNDO
which allows unlimited log file growth for long transactions seems like
a loser to me.

Actually, that brings up a question I had. In 7.1.0, we didn't recycle
WAL segements that were used by open transactions during CHECKPOINT,
while in 7.1.3 and later, we do recycle them after CHECKPOINT.  My
question is if we do a big transaction that needs 10 log segments, do we
force an early CHECKPOINT to clear out the WAL segments or do we just
wait for the proper interval?

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