Re: Parallel Aggregates for string_agg and array_agg
От | Tom Lane |
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Тема | Re: Parallel Aggregates for string_agg and array_agg |
Дата | |
Msg-id | 18741.1522245278@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: Parallel Aggregates for string_agg and array_agg (Tomas Vondra <tomas.vondra@2ndquadrant.com>) |
Ответы |
Re: Parallel Aggregates for string_agg and array_agg
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Список | pgsql-hackers |
Tomas Vondra <tomas.vondra@2ndquadrant.com> writes: > On 03/28/2018 05:28 AM, Tom Lane wrote: >> Getting a solution that would work for other polymorphic serialization >> functions seems like a bit of a research project to me. In the meantime, >> I think David's right that what we need to look at is the actual input >> type of the aggregate, and then assume that what's to be serialized is >> an array of that. Conceivably an aggregate could be built that uses >> these serial/deserial functions and yet its input type is something else >> than what it constructs an array of ... but I find it a bit hard to >> wrap my brain around what that would be exactly. > But David's fix doesn't check the aggregate to produce an array of the > input type (or anyarray). It could easily be an aggregate computing a > bloom filter or something like that, which has no such issues in the > serial/deserial functions. Oh, if he's not restricting it to these serialization functions, I agree that seems wrong. I thought the discussion was about what to do after checking the functions. > Also, if it's checking aggref->aggargtypes, it'll reject anyelement > parameters, no? I had in mind to look at exprType() of the argument. regards, tom lane
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