From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | hannu(at)trust(dot)ee (Hannu Krosing) |
Cc: | jwieck(at)debis(dot)com, hackers(at)postgreSQL(dot)org |
Subject: | Re: [HACKERS] 6.5 beta and ORDER BY patch |
Date: | 1999-02-03 18:46:22 |
Message-ID: | 199902031846.NAA04692@candle.pha.pa.us |
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Thread: | |
Lists: | pgsql-hackers |
> Next thing to attack then would be aggregates, so that they too can
> benefit from indexes, I can immediately think of MIN, MAX and COUNT
> on simple scans. But as the aggregates are user-defined, we probably
> need a flag that tells the optimiser if said aggregate can in fact
> use indexes (and what type of index)
>
> Maybe we can even cache some data (for example tuple count) in
> backend, so that COUNT(*) can be made real fast ?
>
> After that the reverse index scans, so that the index that are
> backwards can also be used for sorting.
> BTW, can this be easily implemented/effective in PostgreSQL or are
> our btree indexes optimised for forward scans ?
Jan, I have kept the postings on optimizing LIMIT for joins. Let me
know if/when you want to see them.
--
Bruce Momjian | http://www.op.net/~candle
maillist(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
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