Re: Reducing relation locking overhead

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. Since it would probably
be problematic and expensive to check for this every time you accessed a
table, it would make sense to check only at the start of a transaction
and have an index build wait until all running transactions knew that an
index build was going to happen.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461