Re: Error trying to create a functional index.
От | Jochem van Dieten |
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Тема | Re: Error trying to create a functional index. |
Дата | |
Msg-id | 3C3AD7A0.9090304@dev.null обсуждение исходный текст |
Ответ на | Re: Error trying to create a functional index. (CoL <col@mportal.hu>) |
Список | pgsql-sql |
CoL wrote: > Steve: of course you can make functional indices: > > So why this not workin???? (not workin for me 2 too, pg 7.1.3) > "CREATE INDEX eventdateindex ON event (date_trunc('day', eventstamp));" > > ---------------- > 7.5. Functional Indices > For a functional index, an index is defined on the result of a function > applied to one or more columns of a single table. Functional indices can > be used to obtain fast access to data based on the result of function > calls. > For example, a common way to do case-insensitive comparisons is to use > the lower: > SELECT * FROM test1 WHERE lower(col1) = 'value'; > In order for that query to be able to use an index, it has to be defined > on the result of the lower(column) operation: > CREATE INDEX test1_lower_col1_idx ON test1 (lower(col1)); > The function in the index definition can take more than one argument, > but they must be table columns, not constants. Wouldn't your problem be that 'day' is a constant? Jochem
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