Re: Temp tables and LRU-K caching - Mailing list pgsql-hackers

From Mike Mascari
Subject Re: Temp tables and LRU-K caching
Date
Msg-id 3D8F4416.9070808@mascari.com
Whole thread Raw
In response to Temp tables and LRU-K caching  (Mike Mascari <mascarm@mascari.com>)
List pgsql-hackers
Tom Lane wrote:
> Mike Mascari <mascarm@mascari.com> writes:
> 
>>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?
> 
> No, we never heard back from that guy.  It is still a live topic though.
> One of the Red Hat people was looking at it over the summer, and I think
> Neil Conway is experimenting with LRU-2 code right now.

Okay.

> 
>>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?
> 
> 
> No they didn't; I forget whether there was any objection to his last try
> or it was just too late to get reviewed before feature freeze.

Nuts. Oh well. Hopefully for 7.4...

> 
>>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?
> 
> 
> A completely-in-memory temp table is not really practical in Postgres,
> for two reasons: one being that its schema information is stored in
> the definitely-not-temp system catalogs, and the other being that we
> request allocation of disk space for each page of the table, even if
> it's temp.  

I knew what I was asking made no sense two seconds after 
clicking 'Send'. Unfortunately, there's no undo on my mail 
client ;-).

Mike Mascari
mascarm@mascari.com





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