Concate string path in psql command line

Question

I have to merge path directory and actual time in psql command line. This absolute path works well:

\copy (select row_to_json(row(column1,column5)) from testdatabase.test) TO 'C:\Users\path\file.json';

But when I want merge two string like this:

\copy (select row_to_json(row(column1,column5)) from testdatabase.test) TO 'C:\Users\path\' || to_char(now(), 'YYYY_MM_DD');

I get Permission denied. This is permission issue i think because first request works well on same path. I tried also CONCATE statement but it fails.

Answer 1

If using COPY directly is an option, you could dynamically build the command, including your custom path logic and EXECUTE it. For example in an anonymous DO block:

DO
$$
BEGIN
  EXECUTE 'COPY (SELECT row_to_json(...) ...) TO ''C:\...\' || to_char(now(), 'YYYY_MM_DD') || '.json''';
END;
$$
LANGUAGE plpgsql;