Re: [PROPOSAL] Max recursion depth in WITH Queries (Common Table Expressions)
От | Valery Popov |
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Тема | Re: [PROPOSAL] Max recursion depth in WITH Queries (Common Table Expressions) |
Дата | |
Msg-id | 5630E28E.6070409@postgrespro.ru обсуждение исходный текст |
Ответ на | Re: [PROPOSAL] Max recursion depth in WITH Queries (Common Table Expressions) (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: [PROPOSAL] Max recursion depth in WITH Queries (Common Table Expressions)
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Список | pgsql-hackers |
28.10.2015 16:33, Tom Lane пишет: > Valery Popov <v.popov@postgrespro.ru> writes: >> Recursive queries are typically used to deal with hierarchical or >> tree-structured data. >> In some conditions when data contain relationships with cycles recursive query will loop >> unlimited and significantly slows the client's session. > The standard way of dealing with that is to include logic in the query to > limit the recursion depth, for example > > WITH RECURSIVE t(n) AS ( > SELECT 1 > UNION ALL > SELECT n+1 FROM t WHERE n < 10 > ) > SELECT n FROM t; > Yes, I agree with this thesis. But I think in some cases would be better to receive error message and stop execution than results will incomplete. -- Regards, Valery Popov Postgres Professional http://www.postgrespro.com The Russian Postgres Company
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