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Re: 8.1 (win32): partial index not used?



i've noticed a problem with an index, where the index wouldn't be used anymore as soon as a partial condition is added.

please ignore my partial index problem. of course i would have to define the partial index part correctly:

it works just fine this way:
movies_folder_idx: USING btree ((lower((mov_folder)::text))) WHERE (lower((mov_folder)::text) <> ''::text);

still, 0.2ms for querying an index containing ~3000 entries seems quite long:

SELECT * FROM oldtables.movies WHERE lower(mov_folder) = 'harrypotter5' AND mov_year = 2007 LIMIT 1

Limit (cost=5.67..9.68 rows=1 width=232) (actual time=0.084..0.084 rows=1 loops=1) -> Bitmap Heap Scan on movies (cost=5.67..9.68 rows=1 width=232) (actual time=0.081..0.081 rows=1 loops=1) Recheck Cond: ((lower((mov_folder)::text) = 'harrypotter5'::text) AND (mov_year = 2007)) -> BitmapAnd (cost=5.67..5.67 rows=1 width=0) (actual time=0.075..0.075 rows=0 loops=1) -> Bitmap Index Scan on movies_folder_idx (cost=0.00..2.64 rows=182 width=0) (actual time=0.034..0.034 rows=1 loops=1) Index Cond: (lower((mov_folder)::text) = 'harrypotter5'::text) -> Bitmap Index Scan on movies_mov_year_idx (cost=0.00..2.78 rows=222 width=0) (actual time=0.036..0.036 rows=62 loops=1)
                   Index Cond: (mov_year = 2007)
Total runtime: 0.217 ms

any tipps?
- thomas





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