Re: Reducing relation locking overhead

Ühel kenal päeval, N, 2005-12-08 kell 00:16, kirjutas Jim C. Nasby:
> On Sat, Dec 03, 2005 at 10:15:25AM -0500, Greg Stark wrote:
> > Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> > > What's worse, once you have excluded writes you have to rescan the entire
> > > table to be sure you haven't missed anything. So in the scenarios where this
> > > whole thing is actually interesting, ie enormous tables, you're still
> > > talking about a fairly long interval with writes locked out. Maybe not as
> > > long as a complete REINDEX, but long.
> >
> > I was thinking you would set a flag to disable use of the FSM for
> > inserts/updates while the reindex was running. So you would know where to find
> > the new tuples, at the end of the table after the last tuple you read.
>
> What about keeping a seperate list of new tuples? Obviously we'd only do
> this when an index was being built on a table.

The problem with separate list is that it can be huge. For example on a
table with 200 inserts/updates per second an index build lasting 6 hours
would accumulate total on 6*3600*200 = 4320000 new tuples.

----------------
Hannu