Re: cardinality()
От | Tom Lane |
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Тема | Re: cardinality() |
Дата | |
Msg-id | 13073.1235929216@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: cardinality() (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: cardinality()
Re: cardinality() Re: cardinality() |
Список | pgsql-hackers |
I wrote: > The standard doesn't have multi-dimensional arrays, so it's entirely > possible that somewhere in it there is wording that makes cardinality() > equivalent to the length of the first dimension. But I concur with > Andrew that this is flat wrong when extended to m-d arrays. I poked around in the SQL:2008 draft a bit. AFAICT the most precise statement about cardinality() is in 6.27 <numeric value function>: <cardinality expression> ::= CARDINALITY<left paren> <collection value expression> <right paren> 7) The result of <cardinality expression> is the number of elements of the result of the <collection value expression>. Now the standard is only considering 1-D arrays, but I fail to see any way that it could be argued that the appropriate reading of "number of elements" for a multi-D array is the length of the first dimension. So I think Andrew is right and we need to fix our implementation of cardinality() while we still can. regards, tom lane
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