This works, but surely there is a better way to do it:
What do you mean by "better"?
select jsonb_agg(row_to_json(alias)) from
(Select * from jsonb_populate_recordset(null::tx_portal, json_table2) order by portal_name) alias
into json_table2;
It sorts the json_table2 array in "portal_name" order.
The only other possibility would be:
CREATE TABLE json_table2 AS
select jsonb_agg(row_to_json(alias) order by portal_name) from
(select * from jsonb_populate_recordset(...)) alias;
i.e., move the order by into the aggregate; I prefer CREATE TABLE AS over SELECT INTO ...
I don't know why you are thinking there is a better way...you are doing two distinct actions here and you have two invocations of select...seems like the minimal possible number of sub-statements to me. No one has written a c-language function for core that provides a more friendly interface to this. Looking at your query doing so using dynamic SQL within a pl/pgsql function would seem reasonably easy.
I would suggest not using "json_table2" as both the name of the input variable and the target table name - it can be confusing to follow when you overload names like that.
