From: | Celia McInnis <celia(dot)mcinnis(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: How do I insert and update into a table of arrays of composite types via a select command? |
Date: | 2017-10-25 21:16:09 |
Message-ID: | CAGD6t7+5rbpCd=pT8CzGNyXAVNSY7PB8kEft9znMRK0FSMpmDQ@mail.gmail.com |
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Lists: | pgsql-general |
Got it, finally...
insert into t_array select array[row((data_comp).*)::mytype[] from
t_composite;
I'm not sure why I need (data_comp).* rather than some of the other things
that I tried and failed with...
On Wed, Oct 25, 2017 at 3:47 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Celia McInnis <celia(dot)mcinnis(at)gmail(dot)com> writes:
> > My first question is: HOW do I populate this table, at first with arrays
> > containing one element from the t_composite table?
> > I have tried various things with no success.
>
> You didn't say what you tried, but I imagine it was something like
>
> regression=# insert into t_array select array[row('a','b','c'),row('d'
> ,'e','f')];
> ERROR: column "data_array" is of type mytype[] but expression is of type
> record[]
> LINE 1: insert into t_array select array[row('a','b','c'),row('d','e...
> ^
> HINT: You will need to rewrite or cast the expression.
>
> Like it says, you need a cast. You can either cast the array elements
> individually:
>
> regression=# insert into t_array select array[row('a','b','c')::
> mytype,row('d','e','f')::mytype];
> INSERT 0 1
>
> or just cast the whole ARRAY[] construct:
>
> regression=# insert into t_array select array[row('a','b','c'),row('d'
> ,'e','f')]::mytype[];
> INSERT 0 1
>
> although I think the latter only works in relatively late-model
> Postgres, and it might make parsing a bit slower too.
>
> regards, tom lane
>
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