| From: | Grzegorz Jaskiewicz <gj(at)pointblue(dot)com(dot)pl> |
|---|---|
| To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
| Cc: | PostgreSQL-development Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: cardinality() |
| Date: | 2009-03-01 11:22:44 |
| Message-ID: | 625B8158-CCE7-4D84-ACE1-6D1964145018@pointblue.com.pl |
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| Thread: | |
| Lists: | pgsql-hackers |
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.
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