The thing I can't really understand why can't the planner find out something
like this:
1. Index scan using column6
2. Backward search on subset using column3
Any guru to explain?
G.
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----- Original Message -----
From: "Kevin Schroeder" <mirage@mirageworks.com>
Sent: Thursday, May 29, 2003 4:09 PM
> I figured out how to make the query faster. There should be a mailing
list
> set up for wasted questions since I always seem to figure out the problem
> after I've bugged everyone for help.
>
> In the query
>
> select row_key, column1, column2, column3, column4, column5 from table1
> where column6 = 1 order by column3 desc limit 21;
>
> I changed the index to
>
> message_index btree (column3, column6)
>
> rather than
>
> message_index btree (column6, column3, column7)
>
> Since the data was being ordered by column3 it seems to have sped the
query
> up to 1 ms from 6000ms by making column 3 the first part of the index
rather
> than the second.
>
> Kevin