stacker.news/prisma/migrations/20230509171046_comment_weig.../migration.sql

50 lines
2.0 KiB
MySQL
Raw Normal View History

2023-05-09 18:52:35 +00:00
UPDATE "Item"
SET "weightedComments" = sub."weightedComments"
FROM (
SELECT subsub."itemId", SUM(subsub."userTrust") AS "weightedComments"
FROM
(SELECT p.id AS "itemId", u.id AS "userId", u.trust AS "userTrust"
FROM "Item" p
-- all decendants of p that aren't from the same author
JOIN "Item" c ON c.path <@ p.path AND c.id <> p.id AND c."userId" <> p."userId"
JOIN users u ON u.id = c."userId"
WHERE u.trust > 0
GROUP BY p.id, u.id, u.trust) subsub
GROUP BY subsub."itemId") sub
WHERE "Item".id = sub."itemId";
-- TODO: this could be better, e.g. testing for comment length or using comment votes instead
-- of just comment presence ... this is just an mvp
CREATE OR REPLACE FUNCTION ncomments_after_comment() RETURNS TRIGGER AS $$
DECLARE
user_trust DOUBLE PRECISION;
BEGIN
-- grab user's trust who is commenting
SELECT trust INTO user_trust FROM users WHERE id = NEW."userId";
UPDATE "Item"
SET "lastCommentAt" = now_utc(), "ncomments" = "ncomments" + 1
WHERE id <> NEW.id and path @> NEW.path;
-- we only want to add the user's trust to weightedComments if they aren't
-- already the author of a descendant comment
UPDATE "Item"
SET "weightedComments" = "weightedComments" + user_trust
FROM (
-- for every ancestor of the new comment, return the ones that don't have
-- the same author in their descendants
SELECT p.id
FROM "Item" p
-- all decendants of p that aren't the new comment
JOIN "Item" c ON c.path <@ p.path AND c.id <> NEW.id
-- p is an ancestor of this comment, it isn't itself, and it doesn't have the same author
WHERE p.path @> NEW.path AND p.id <> NEW.id AND p."userId" <> NEW."userId"
GROUP BY p.id
-- only return p if it doesn't have any descendants with the same author as the comment
HAVING bool_and(c."userId" <> NEW."userId")
) fresh
WHERE "Item".id = fresh.id;
RETURN NEW;
END;
$$ LANGUAGE plpgsql;