Re: Remove xmin and cmin from frozen tuples

On Fri, 2 Sep 2005 20:41:48 -0400 (EDT), Bruce Momjian
<pgman@candle.pha.pa.us> wrote:
>> Once I had a patch based on 7.4 that stored cmin and cmax in
>> backend-local memory.

>Interesting idea, but how would you record the cmin/xmin values without
>requiring unlimited memory?

That's exactly the reason for not sending it to -patches.  Without
spilling to disk this is just not ready for real life.  The problem is
that -- unlike other data structures that build up during a
transaction, e.g. trigger queues -- cmin/cmax lookup requires random
access, so we'd need some form of tree or hash.  Unfornunately I never
got beyond brainstorming :-(

BTW, is there anything else that'd need spilling to disk during long
transactions?

Servus
 Manfred