Thanks Tom - I saw how to do that for specified data, but I want to select the elements from a table of composite and don't know how to do that. I can't do insertions manually of each row separately! So how do I get material from my table of composite values into my table of array values?
I am running postgresql 9.6.2.
On Wed, Oct 25, 2017 at 3:47 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Celia McInnis <celia.mcinnis@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.
