Re: Pre-allocated free space for row updating (like PCTFREE)

Tom Lane wrote:
> I'm not very enthused about this.  Enforcing 12.5% PCTFREE means that
> you pay 12.5% extra I/O costs across the board for INSERT and SELECT
> and then hope you can make it back (plus some more) on UPDATEs.
> pgbench is a completely UPDATE-dominated benchmark and thus it makes
> such a patch look much better than it would on other workloads.

Yes. I'm thinking about update-intensive workload or batch jobs
which generate huge amounts of updates.

I know pgbench is just a update-intensive benchmark, however
I don't like updates cause many smgrextend() and performance down,
because there are many workload types in the real-world.

I believe some of us need more options for these types of workloads.

(And I also know we need more tricks on page repair.)

> I think the reason Oracle offers this has to do with their
> overwrite-based storage management; it's not obvious that the tradeoff
> is as useful for us.  There are some relevant threads in our archives
> here, here, and here:

I think the reason why this topic is raised many times is
some people need this.

The important point is that we need several options
for own workloads (or access patterns).

-- 
NAGAYASU Satoshi <nagayasus@nttdata.co.jp>