On 2004-12-06, Pierre-Frédéric Caillaud <lists@boutiquenumerique.com>
wrote:
> SELECT * FROM test WHERE (name='b' and name2>'a') OR (name>'b') ORDER BY
> name,name2 ASC LIMIT 1;
Write that WHERE clause instead as:
WHERE name>='b' AND (name>'b' OR (name='b' AND name2>'a'))
This is logically equivalent, but it gives the planner a better handle on
how to use an index scan to satisfy the query.
> SELECT * FROM test WHERE (name='b' and name2<'a') OR (name<'b') ORDER BY
> name,name2 DESC LIMIT 1;
That needs to be ORDER BY name DESC, name2 DESC (the direction indicator
applies per-column and not to the output ordering). Same goes for the
WHERE clause in this query as the previous one, too.
--
Andrew, Supernews
http://www.supernews.com - individual and corporate NNTP services