Is it possible to get the query plan for an SQL statement executed inside a user defined function (UDF)? Like with using EXPLAIN
in pgAdmin or psql as client. I see the UDF abstracted away into a single operation F()
in pgAdmin.
Currently, I pull out statements and run them manually. But this isn't going to cut it for large queries.
For example, consider the UDF below. It can print its dynamically generated query string. But that can't be run separately as it depends on a temporary table created in the local context.
CREATE OR REPLACE FUNCTION get_paginated_search_results(
forum_id_ INTEGER,
query_ CHARACTER VARYING,
from_date_ TIMESTAMP WITHOUT TIME ZONE DEFAULT NULL,
to_date_ TIMESTAMP WITHOUT TIME ZONE DEFAULT NULL,
in_categories_ INTEGER[] DEFAULT '{}')
RETURNS SETOF post_result_entry AS $$
DECLARE
join_string CHARACTER VARYING := ' ';
from_where_date CHARACTER VARYING := ' ';
to_where_date CHARACTER VARYING := ' ';
query_string_ CHARACTER VARYING := ' ';
BEGIN
IF NOT from_date_ IS NULL THEN
from_where_date := ' AND fp.posted_at > ''' || from_date_ || '''';
END IF;
IF NOT to_date_ IS NULL THEN
to_where_date := ' AND fp.posted_at < ''' || to_date_ || '''';
END IF;
CREATE LOCAL TEMP TABLE un_cat(id) ON COMMIT DROP AS (select * from unnest(in_categories_)) ;
if in_categories_ != '{}' THEN
join_string := ' INNER JOIN forum_topics ft ON fp.topic_id = ft.id ' ||
' INNER JOIN un_cat uc ON uc.id = ft.category_id ' ;
END IF;
query_string_ := '
SELECT index,posted_at,post_text,name,join_date,quotes
FROM forum_posts fp
INNER JOIN forum_user fu ON
fu.forum_id = fp.forum_id AND fu.id = fp.user_id' ||
join_string
||
'WHERE fu.forum_id = ' || forum_id_ || ' AND
to_tsvector(''english'',fp.post_text) @@ to_tsquery(''english'','''|| query_||''')' ||
from_where_date ||
to_where_date
||';';
RAISE NOTICE '%', query_string_ ;
RETURN QUERY
EXECUTE query_string_;
END;
$$ LANGUAGE plpgsql;