On Sat, Jun 29, 2019 at 3:51 PM Julien Rouhaud <rjuju...@gmail.com> wrote: > On Sat, Jun 29, 2019 at 12:25 PM Tomas Vondra > <tomas.von...@2ndquadrant.com> wrote: > > > > On Sat, Jun 29, 2019 at 11:10:03AM +0200, Julien Rouhaud wrote: > > >On Sat, Jun 29, 2019 at 12:51 AM Nikita Glukhov > > >> -- patched > > >> EXPLAIN ANALYZE SELECT * FROM test WHERE t LIKE '%1234%' AND t LIKE > > >> '%1%'; > > >> QUERY PLAN > > >> ----------------------------------------------------------------------------------------------------------------------- > > >> Bitmap Heap Scan on test (cost=20.43..176.79 rows=42 width=6) (actual > > >> time=0.287..0.424 rows=300 loops=1) > > >> Recheck Cond: ((t ~~ '%1234%'::text) AND (t ~~ '%1%'::text)) > > >> Rows Removed by Index Recheck: 2 > > >> Heap Blocks: exact=114 > > >> -> Bitmap Index Scan on test_t_idx (cost=0.00..20.42 rows=42 > > >> width=0) (actual time=0.271..0.271 rows=302 loops=1) > > >> Index Cond: ((t ~~ '%1234%'::text) AND (t ~~ '%1%'::text)) > > >> Planning Time: 0.080 ms > > >> Execution Time: 0.450 ms > > >> (8 rows) > > > > > >One thing that's bothering me is that the explain implies that the > > >LIKE '%i% was part of the index scan, while in reality it wasn't. One > > >of the reason why I tried to modify the qual while generating the path > > >was to have the explain be clearer about what is really done. > > > > Yeah, I think that's a bit annoying - it'd be nice to make it clear > > which quals were actually used to scan the index. It some cases it may > > not be possible (e.g. in cases when the decision is done at runtime, not > > while planning the query), but it'd be nice to show it when possible. > > Maybe we could somehow add some runtime information about ignored > quals, similar to the "never executed" information for loops?
+1, This sounds reasonable for me. ------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
