Re: Temp tables and LRU-K caching

Mike Mascari wrote:
> Hello.
>
> I'm just curious as to the 7.3 status of a couple of things:
>
> 1. Back in Feb. I wrote (in regards to Oracle behavior):
>
> "Unlike normal queries where blocks are added to the MRU end of
> an LRU list, full table scans add the blocks to the LRU end of
> the LRU list. I was wondering, in the light of the discussion of
> using LRU-K, if PostgreSQL does, or if anyone has tried, this
> technique?"
>
> Bruce wrote:
>
> "Yes, someone from India has a project to test LRU-K and MRU for
> large table scans and report back the results. He will
> implement whichever is best."
>
> Did this make it into 7.3?

That person stopped working on it. It is still on the TODO list.

> 2. Gavin Sherry had worked up a patch so that temporary
> relations could be dropped automatically upon transaction
> commit. Did any of those patches it make it? I notice that
> whenever I create a temporary table in a transaction, my HD
> light blinks. Is this a forced fsync() causes by the fact that
> the SQL standard defines temporary relations as surviving across
> transactions? If so, I'd bet those of us who use
> transaction-local temporary tables could get few drops more of
> performance from an ON COMMIT drop patch w/o fsync.

This has me confused. There was an exchange with Gavin Auguest 27/28
which resulted in a patch:

http://archives.postgresql.org/pgsql-patches/2002-08/msg00475.php

and my adding it to the patches list:

http://archives.postgresql.org/pgsql-patches/2002-08/msg00502.php

However, it was never applied. I don't see any discussion refuting the
patch or any email removing it from the queue. The only thing I can
think of is that somehow I didn't apply it.

My only guess is that I said I was putting in the queue, but didn't. I
am concerned if there are any other patches I missed. I see the cube
patch being added to the queue 40 seconds later, and I know that was in
there because I see the message removing it from the queue. I must have
made a mistake on that one.

What do we do now? The author clearly got it in before beta, but we are
in beta now. I think we should apply it.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073