Re: update substring pattern matching syntax
От | Fabien COELHO |
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Тема | Re: update substring pattern matching syntax |
Дата | |
Msg-id | alpine.DEB.2.22.394.2006200835570.859381@pseudo обсуждение исходный текст |
Ответ на | update substring pattern matching syntax (Peter Eisentraut <peter.eisentraut@2ndquadrant.com>) |
Ответы |
Re: update substring pattern matching syntax
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Список | pgsql-hackers |
Hello Peter, > whereas the current standard says > > SUBSTRING(text SIMILAR pattern ESCAPE escapechar) > > The former was in SQL99, but the latter has been there since SQL:2003. > > It's pretty easy to implement the second form also, so here is a patch that > does that. Patches apply cleanly, compile and "make check" is ok. doc gen is ok as well. Grammar cleanup is a definite improvement as it makes the grammar closer to the actual syntax. I cannot say I'm a fan of this kind of keywords added for some arguments. I guess that it allows distinguishing between variants. I do not have the standard at hand: I wanted to check whether these keywords could be reordered, i.e. whether SUBSTRING(text ESCAPE ec SIMILAR part) was legal. I guess not. Maybe the doc could advertise more systematically whether a features conforms fully or partially to some SQL standards, or is pg specific. The added documentation refers both to SQL:1999 and SQL99. I'd suggest to chose one, possibly the former, and use it everywhere consistently. It seems that two instances where not updated to the new syntax, see in ./src/backend/catalog/information_schema.sql and ./contrib/citext/sql/citext.sql. -- Fabien.
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