Re: XLOG_BLCKSZ vs. wal_buffers table

> > > I'm planning on continuing to increase XLOG_BLCKSZ and wal_buffers
to
> > > determine when the throughput starts to level out or drop
> >
> > I think for an even better comparison you should scale wal_buffers
> > down with increasing XLOG_BLCKSZ, so that the xlog buffer has a
fixed
> > size in kb.
> >
> > Reasonable wal_buffers imho amount to at least 256kb, better yet 512
or 1 Mb,
> > with sufficiently large transactions (and to try to factor out the
difference
> > between blocksizes).
>
> AFAIK all the transactions in DBT2 are pretty small. I think all DML
is
> single-row in fact, so I'm not sure that having wal_buffers much
larger
> than the number of connections would help much.

Well, but those updates wander around the whole table/index, so you will
have a lot of
before images to write. So I take back the "sufficiently large
transactions" part
of my comment. You want more wal_buffers in all higher load scenarios.

(one test had 8 buffers of 2k each, this is not enough in any high load
scenario)

Andreas