multicolumn index join
От | Stephen Ince |
---|---|
Тема | multicolumn index join |
Дата | |
Msg-id | 12d001c8b50d$ea91b8c0$6e00a8c0@desktop2 обсуждение исходный текст |
Ответ на | Stripping out slony after / before / during pg_restore? (Glyn Astill <glynastill@yahoo.co.uk>) |
Ответы |
Re: multicolumn index join
Re: multicolumn index join |
Список | pgsql-general |
I have to do a multicolumn self-join to find the median. I am using postgres 8.2. How do I force postgres to use an index scan? I have a multicolumn index but postgres is not using it. Query ------------------------------------ explain select e.time from page_view e, page_view d where e.test_run_id = d.test_run_id and e.web_resource_id = d.web_resource_id and e.web_resource_id = 3961 and e.test_run_id = 2 1 index ----------------------------------------------------------------------- create index page_view_page_idx ON page_view(test_run_id, web_resource_id); primar key -------------------------------------- (test_run_id,page_view_id) plan -------------------------------------------------------------- "Nested Loop (cost=127.58..13592618.11 rows=33489369 width=8)" " -> Seq Scan on page_view e (cost=0.00..3291.26 rows=5787 width=16)" " Filter: ((web_resource_id = 3961) AND (test_run_id = 2))" " -> Bitmap Heap Scan on page_view d (cost=127.58..2290.38 rows=5787 width=8)" " Recheck Cond: ((3961 = web_resource_id) AND (2 = test_run_id))" " -> Bitmap Index Scan on page_view_page_idx (cost=0.00..126.13 rows=5787 width=0)" " Index Cond: ((3961 = web_resource_id) AND (2 = test_ Steve
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