Re: Index on immutable function call

Поиск
Список
Период
Сортировка
От Dean Rasheed
Тема Re: Index on immutable function call
Дата
Msg-id 8e2dbb701001190554q1d27fd10k71f9e39e5982aa6d@mail.gmail.com
обсуждение исходный текст
Ответ на Re: Index on immutable function call  ("Philippe Lang" <philippe.lang@attiksystem.ch>)
Ответы Re: Index on immutable function call  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-general
2010/1/19 Philippe Lang <philippe.lang@attiksystem.ch>:
> That works just fine, but is there maybe a way of creating a slighly
> more "generic" index? If I change the ">" with a "<" in the query, index
> cannot of course be used. According to documentation, answer seems to be
> "no"...
>

You could create an index on the difference:

create index long_transformation_index on indexed_table
((data1-this_is_a_long_transformation(data2)));

then rewrite your queries accordingly:

... WHERE data1-this_is_a_long_transformation(data2) > some const (or
< some const)

HTH,
Dean

В списке pgsql-general по дате отправления:

Предыдущее
От: "Philippe Lang"
Дата:
Сообщение: Re: Index on immutable function call
Следующее
От: Tom Lane
Дата:
Сообщение: Re: Index on immutable function call