Re: COPY Fillfactor patch

My guess is that the FILLFACTOR will actually be a GUC variable rather
than a clause to CREATE INDEX or REINDEX or CLUSTER.

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Hannu Krosing wrote:
> On T, 2005-04-12 at 18:38 +0100, Simon Riggs wrote:
> > On Tue, 2005-04-12 at 09:56 -0400, Tom Lane wrote:
>
> (Neil, I added you to CC: to show you at least two more places where
> sparse heaps can be generally useful and not tweaks for single
> benchmark)
>
> > > Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > > > During recent tuning of the TPC-C workload, I produced the following
> > > > patch to force COPY to leave some space in each data block when it loads
> > > > data into heap relations.
>
> When I comtemplated a similar idea some time ago, my primary goal was
> reducing disk head movement during massive updates.
>
> At that time it seemed to me cheaper to not leave space in each page,
> but to leave each Nth page empty, as more new tuples will be punt on the
> same page and thus cause less WAL writes.
>
> Warning: This may be a false assumption - I did not check from code, if
> this is actually so for any or even a significant number of cases.
>
> > > Put the info into the Relation
> > > structure instead of cluttering heap_insert's API. (This would mean
> > > that *every* heap_insert is affected, not only COPY, which is what you
> > > want anyway I would think.)
> >
> > Well, I intended it to work *only* for copy, not for insert, which is
> > why I did it that way.
>
> To be more generally useful similar thing should be added to VACUUM FULL
> and CLUSTER.
>
> And perhaps some weird LAZY version of "VACUUM EXPAND" could be written
> as well, for keeping the holes from filling up in constantly growing
> databases.
>
> Having these holes is also essential, if we want a cheap way to keep
> data in CLUSTER order after initial CLUSTER command - if we do have free
> space everywhere in the file, we can just put each new tuple on the
> first page with free space on or after its preceeding tuple in cluster
> index.
>
> > Anyway, when I get time, I'll finish off the patch. Unless other readers
> > would like to follow on.
>
> I hope you will you will get that time before 8.1 ships :)
>
> --
> Hannu Krosing <hannu(at)tm(dot)ee>
>
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>

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