Re: cardinality()
От | Andrew Dunstan |
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Тема | Re: cardinality() |
Дата | |
Msg-id | 49AAAA26.3080901@dunslane.net обсуждение исходный текст |
Ответ на | Re: cardinality() (Grzegorz Jaskiewicz <gj@pointblue.com.pl>) |
Ответы |
Re: cardinality()
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Список | pgsql-hackers |
Grzegorz Jaskiewicz wrote: > > On 1 Mar 2009, at 00:52, Andrew Dunstan wrote: > >> >> We seem to have acquired a cardinality() function with almost no >> discussion, and it has semantics that are a bit surprising to me. I >> should have thought cardinality(array) would be the total number of >> elements in the array. Instead, it seems it is a synonym for >> array_length(array,1). Is that *really* what the standard says? > > any difference between array_upper(array,1), and cardinality ? > Standart just says something like: > > cardinality (a collection): > - The number of elements in that collection. > - Those elements need not necessarily have distinct values. > - The objects to which this concept applies includes tables and the > values of collection types. > Well, I think that's a definition of the term as used in the standard, rather than of a function. But in any case, I think it goes in the right direction, and the semantics of our new function (as well as the docs) are misleading. I'm also a bit concerned that I could not find any real discussion of this new function at all on this list, so our processes seem to have slipped a bit. cheers andrew
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