index scan with functional indexes
От | Dave Cramer |
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Тема | index scan with functional indexes |
Дата | |
Msg-id | 1075213610.1611.287.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: returning PGresult as xml (Andrew Dunstan <andrew@dunslane.net>) |
Ответы |
Re: index scan with functional indexes
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Список | pgsql-hackers |
I'm curious what the result of a reverse index does on a table with url like data, so I did the following create function fn_strrev(text) returns text as 'return reverse($_[0])' language 'plperl' with (iscachable); create index r_url_idx on url( fn_strrev(url)); vacuum analyze; explain select * from url where url like fn_strrev('%beta12.html'); QUERY PLAN ---------------------------------------------------------Seq Scan on url (cost=0.00..13281.70 rows=1 width=454) Filter:((url)::text ~~ 'lmth.21ateb%'::text) Is it possible to get the planner to use an index scan ? How? the db is using locale 'C' -- Dave Cramer 519 939 0336 ICQ # 1467551
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