Re: PostgreSQL Indexing versus MySQL
От | Lincoln Yeoh |
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Тема | Re: PostgreSQL Indexing versus MySQL |
Дата | |
Msg-id | 5.2.1.1.1.20040218183328.0274b060@mbox.jaring.my обсуждение исходный текст |
Ответ на | Re: PostgreSQL Indexing versus MySQL ("scott.marlowe" <scott.marlowe@ihs.com>) |
Ответы |
Re: PostgreSQL Indexing versus MySQL
Re: PostgreSQL Indexing versus MySQL |
Список | pgsql-general |
At 04:14 PM 2/17/2004 -0700, scott.marlowe wrote: >custom type (hex, foobar, etc...) from one to another. What this means >too you, the user, is that: > >create table test (id int8, info text); ><insert 10,000 rows> >select * from test where id=456; > >will result in a sequential scan. Why? Because the default integer type >is int4, and your id field is int8. Cast the value to int8, and watch it >use an index scan: > >select * From test where id=cast(456 as int8); Actually won't select * from test where id='456' use the index? I'm curious if this work in all cases - e.g. postgresql figures the best cast for text to whatever, even for relevant custom types?
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