Le 2014-06-17 à 14:22, Condor <[email protected]> a écrit :
> I do select array_agg(ids) from x;
> in ids I have int and result is :
>
> array_agg
> -------------
> {3843,2,3543,33}
>
> I want to access one element or first one direct in sql query like:
>
> select array_agg(ids)[1] from x;
>
> and to receive int value 2
>
> Any hints how I can do it ?
This works for me in 9.1:
psql (9.1.13)
Type "help" for help.
svanalytics=> select (array_agg(x))[1] from (values(3843),(2),(3543),(33))
t1(x) ;
array_agg
-----------
3843
Note the use of the extra parens around the array_agg call. This is probably a
parser issue more than anything else.
> And also for performance did that is good I to do it in SQL or I should do it
> in language that I use ? The result in query will return about 2, 3 million
> rows.
Do you mean you will have an array of 2, 3 million elements, or 2, 3 million
rows with a couple dozen elements each? I’m not sure which will be easier /
faster. I routinely work with million element result sets (rows) and have no
issues.
Hope that helps!
François
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