Question

CREATE OR REPLACE FUNCTION somefunction(ret refcursor, _id oid, _offset integer, _limit integer) RETURNS refcursor
    LANGUAGE plpgsql
    AS $_$
BEGIN
    OPEN $1 FOR
            --My actual select is much more complicated that this.
        SELECT a FROM b
        WHERE id = _id
        ORDER BY otu.id desc
            --does not work: invalid input syntax for integer: "ALL"
        LIMIT (CASE WHEN _limit IS NULL THEN 'ALL' ELSE _limit END)
            --CASE WHEN _limit IS NOT NULL THEN LIMIT _limit END
        OFFSET (CASE WHEN _offset IS NULL THEN '0' ELSE _offset END);
    RETURN $1;

END
$_$;

I want _offset and _limit to be nullable, so all results can be returned. How can I dynamically omit the LIMIT part of this query if _limit is NULL.

The only way I know of doing this is to make the query huge string, which would be ugly.

Answer 1

You can write

LIMIT ALL

to get all rows. Also, I quote the manual:

If the count expression evaluates to NULL, it is treated as LIMIT ALL, i.e., no limit. If start evaluates to NULL, it is treated the same as OFFSET 0

Ergo, simply write:

LIMIT _limit 
OFFSET _offset