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 <t...@sss.pgh.pa.us> wrote:
> Celia McInnis <celia.mcin...@gmail.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
>
