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CREATE FUNCTION @extschema@.check_name_length (
p_object_name text
, p_suffix text DEFAULT NULL
, p_table_partition boolean DEFAULT FALSE
)
RETURNS text
LANGUAGE plpgsql IMMUTABLE
SET search_path TO pg_catalog, pg_temp
AS $$
DECLARE
v_new_name text;
v_suffix text;
BEGIN
/*
* Truncate the name of the given object if it is greater than the postgres default max (63 bytes).
* Also appends given suffix and schema if given and truncates the name so that the entire suffix will fit.
* Returns original name (with suffix if given) if it doesn't require truncation
*/
IF p_table_partition IS TRUE AND (NULLIF(p_suffix, '') IS NULL) THEN
RAISE EXCEPTION 'Table partition name requires a suffix value';
END IF;
v_suffix := format('%s%s', CASE WHEN p_table_partition THEN '_p' END, p_suffix);
-- Use optimistic behavior: in almost all cases `v_new_name` will be less than allowed maximum.
-- Do "heavy" work only in rare cases.
v_new_name := p_object_name || v_suffix;
-- Postgres' relation name limit is in bytes, not characters; also it can be compiled with bigger allowed length.
-- Use its internals to detect where to cut new object name.
IF v_new_name::name != v_new_name THEN
-- Here we need to detect how many chars (not bytes) we need to get from the `p_object_name`.
-- Use suffix as prefix and get the rest of `p_object_name`.
v_new_name := (v_suffix || p_object_name)::name;
-- `substr` starts from 1, that is why we need to add 1 below.
-- Edge case: `v_suffix` is empty, length is 0, but need to start from 1.
v_new_name := substr(v_new_name, length(v_suffix) + 1) || v_suffix;
END IF;
RETURN v_new_name;
END
$$;
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