How can I write to a file on disk from PL/pgSQL?

Question

I would like to do the equivalent of c or php fopen() and fwrite(). I am not trying to dump a table to disk. I am trying to do some debug logging during development.

Answer 1

PostgreSQL 12 + Python 3

    CREATE OR REPLACE FUNCTION "public"."makefile"("path" text, "content" text)
      RETURNS "pg_catalog"."text" AS $BODY$
        import os
        import stat
        o=open(path,'w')
        o.write(content)

        # stat.S_IRUSR Owner has read permission.
        # stat.S_IWUSR Owner has write permission.
        # stat.S_IRGRP Group has read permission.
        # stat.S_IWGRP Group has write permission.
        # stat.S_IROTH Others have read permission.
        os.chmod(path, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IWGRP | stat.S_IROTH)
        o.close()
        return 'ok'
    $BODY$
      LANGUAGE plpython3u VOLATILE