Please help me to improve my SQL function and note that I do not want to switch to PL/pgSQL for performance reasons.
CodePudding user response:
I understand correctly, you can try to use EXISTS
subquery to judgment mute user in words_get_chat
function by your logic.
- if nice user we need to judgment which message they want to see.
- if bad user we can show all of message.
The function might look like as below.
CREATE OR REPLACE FUNCTION words_get_chat(
in_gid integer,
in_social integer,
in_sid text
) RETURNS TABLE (
out_msg text
) AS
$func$
-- TODO display messages by muted users only to themselves
SELECT
c.msg
FROM words_chat c
JOIN words_games g USING (gid)
JOIN words_social s ON s.uid IN (g.player1, g.player2)
WHERE c.gid = in_gid
AND s.social = in_social
AND s.sid = in_sid
AND EXISTS (
SELECT 1
FROM words_users wu
WHERE wu.uid = s.uid AND
((muted = true) OR (muted = false AND c.uid = s.uid))
)
ORDER BY c.CREATED ASC;
CodePudding user response:
Inspired by Daniel's sub query answer and help at the PostgreSQL mailing list, I have developed a CTE and JOIN solution:
CREATE OR REPLACE FUNCTION words_get_chat(
in_gid integer,
in_social integer,
in_sid text
) RETURNS TABLE (
out_mine integer,
out_msg text
) AS
$func$
WITH myself AS (
SELECT uid
FROM words_social
WHERE social = in_social
AND sid = in_sid
LIMIT 1
)
SELECT
CASE WHEN c.uid = myself.uid THEN 1 ELSE 0 END,
c.msg
FROM myself
JOIN words_chat c ON TRUE
JOIN words_games g USING (gid)
JOIN words_users opponent ON (opponent.uid IN (g.player1, g.player2) AND opponent.uid <> myself.uid)
WHERE c.gid = in_gid
-- always show myself my own chat messages
AND c.uid = myself.uid
-- otherwise only show messages by not muted opponents
OR NOT opponent.muted
ORDER BY c.created ASC;
$func$ LANGUAGE sql;