On 08/02/13 01:52, Stefan Keller wrote:
Hi,
I have problems with the performance of FTS in a query like this:
SELECT * FROM FullTextSearch WHERE content_tsv_gin @@
plainto_tsquery('english', 'good');
It's slow (> 30 sec.) for some GB (27886 html files, originally 73 MB zipped).
The planner obviously always chooses table scan: http://explain.depesz.com/s/EEE
I have to check again, if I'm doing something wrong but I'm pretty
sure it has to do with de-toasting and (wrong?) cost estimations.
If you havent done it .. bump up statistics target on the column and
re-analyze, see what that gives.
I have also been playing with the cost-numbers in order to get it to favour
an index-scan more often. That is lowering random_page_cost to be close to
seq_page_cost, dependent on your system, the amount of memory, etc, then
this can have negative side-effects on non-gin-queries.
--
Jesper
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