Thomas H. wrote:
Try putting your conditions as part of the join:
SELECT * FROM shop.dvds
LEFT JOIN
oldtables.movies
ON
mov_id = dvd_mov_id
AND (
lower(mov_name) LIKE '%superman re%'
OR lower(dvd_name) like '%superman re%'
OR lower(dvd_edition) LIKE '%superman re%'
)
LEFT JOIN shop.data_soundmedia ON sm_info_ean = dvd_ean
unfortunately its getting optimized into the same plan :-)
OK - in that case try explicit subqueries:
SELECT ... FROM
(SELECT * FROM shop.dvds
LEFT JOIN shop.oldtables.movies
WHERE lower(mov_name) LIKE ...
) AS bar
LEFT JOIN shop.data_soundmedia
I'd also be tempted to look at a tsearch2 setup for the word searches.
tsearch2 doesn't work that well for exact matches (including special
chars). but the culprit here isn't the '%...'%' seqscan, but rather the
additional joined table (where no lookup except for the join-column
takes place) that makes the query going from 200ms to 24sec.
Agreed, but I'd still be inclined to let tsearch do a first filter then
limit the results with LIKE.
--
Richard Huxton
Archonet Ltd
