Re: [bulk] Re: Problem with LIKE-Performance

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От Tarabas (Manuel Rorarius)
Тема Re: [bulk] Re: Problem with LIKE-Performance
Дата
Msg-id 492687293.20060418180434@tarabas.de
обсуждение исходный текст
Ответ на Re: Problem with LIKE-Performance  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [bulk] Re: Problem with LIKE-Performance  (Richard Huxton <dev@archonet.com>)
Список pgsql-performance
Hi Tom,

TL> As already noted, it might be worth your while to add an index using the
TL> pattern-ops opclass to help with queries like this.

I have done that now and it works very fine as supposed.

The problem with the high startup_costs disappeared somehow after the
change of the enable_seqscan = off and a restart of pg-admin.

first Time I ran the statement it showed 13 sec execution time.

Seq Scan on image image0_  (cost=0.00..21414.21 rows=11 width=1311)
(actual time=10504.138..12857.127 rows=119 loops=1)
  Filter: ((title)::text ~~ '%Davorka%'::text)
Total runtime: 12857.372 ms

second time I ran the statement it dropped to ~500 msec , which is
pretty ok. :-)

Seq Scan on image image0_  (cost=0.00..21414.21 rows=11 width=1311)
(actual time=270.289..552.144 rows=119 loops=1)
  Filter: ((title)::text ~~ '%Davorka%'::text)
Total runtime: 552.708 ms

Best regards
Manuel Rorarius


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