Re: LRU and full table scans

Mike Mascari wrote:
> On general a discussion has been taking place regarding cached query
> plans and how MySQL invented them. Of course, this is totally false. I
> remembered a nice paragraph in the Oracle docs as to the process by
> which Oracle uses shared SQL areas to share the execution plan of
> identical statements, flushing the area whenever a dependent object was
> modified. In searching for the reference, however, I stumbled an
> interesting fact. 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?

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. He posted a week ago, see "Implementation Proposal For Add Free
Behind Capability For Large Sequential Scan", Amit Kumar Khare
<skamit2000(at)yahoo(dot)com>.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026