Re: [GENERAL] btree index on a char(8) field (fwd)
От | Gene Selkov, Jr. |
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Тема | Re: [GENERAL] btree index on a char(8) field (fwd) |
Дата | |
Msg-id | 199910070543.AAA10211@antares.mcs.anl.gov обсуждение исходный текст |
Ответ на | Re: [GENERAL] btree index on a char(8) field (fwd) (Frank Mandarino <fam@risca.com>) |
Ответы |
Re: [GENERAL] btree index on a char(8) field (fwd)
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Список | pgsql-general |
> I am unable to find any reference to bpchar_ops in the the documentation > or the General and SQL mailing list archives. Can you tell me where I > could find out more about what "_ops" are available and what they all > mean? The direct answer: $ pwd /usr/src/postgresql-6.5/doc/src/sgml $ find -name "*sgml" -exec grep -il "_ops" {} \; ./ref/create_index.sgml ./arch-dev.sgml -- irrelevant: co-incidental with a processing directive, \label{simple_set_ops}) ./bki.sgml ./gist.sgml ./xindex.sgml My comment: The deficiency of the docs in regards to operator classes probably results from the fact that no one is asking about those. The opclass parameter in CREATE INDEX is no longer required (Herouth has been around long enough to recall the times when it was). As you have just witnessed, in a standard situation, you are better off without knowing about it -- postgres will pick the right opclass for you. That will not happen, however, when the values you want to index are of a custom type, or when a built-in type does not have an opclass of its own (as is the case with the point type). Also, you need this option to override the default opclass for those types that can work with multiple opclasses (which is what you attempted to achieve). Will anyone with a solid knowledge of the type system want to augment the existing docs? --Gene
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