lemmy/migrations/2023-07-26-000217_create_controversial_indexes/up.sql

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-- Need to add immutable to the controversy_rank function in order to index by it
-- Controversy Rank:
-- if downvotes <= 0 or upvotes <= 0:
-- 0
-- else:
-- (upvotes + downvotes) * min(upvotes, downvotes) / max(upvotes, downvotes)
CREATE OR REPLACE FUNCTION controversy_rank (upvotes numeric, downvotes numeric)
RETURNS float
AS $$
BEGIN
IF downvotes <= 0 OR upvotes <= 0 THEN
RETURN 0;
ELSE
RETURN (upvotes + downvotes) * CASE WHEN upvotes > downvotes THEN
downvotes::float / upvotes::float
ELSE
upvotes::float / downvotes::float
END;
END IF;
END;
$$
LANGUAGE plpgsql
IMMUTABLE;
-- Aggregates
ALTER TABLE post_aggregates
ADD COLUMN controversy_rank float NOT NULL DEFAULT 0;
ALTER TABLE comment_aggregates
ADD COLUMN controversy_rank float NOT NULL DEFAULT 0;
-- Populate them initially
-- Note: After initial population, these are updated with vote triggers
UPDATE
post_aggregates
SET
controversy_rank = controversy_rank (upvotes::numeric, downvotes::numeric);
UPDATE
comment_aggregates
SET
controversy_rank = controversy_rank (upvotes::numeric, downvotes::numeric);
-- Create single column indexes
CREATE INDEX idx_post_aggregates_featured_local_controversy ON post_aggregates (featured_local DESC, controversy_rank DESC);
CREATE INDEX idx_post_aggregates_featured_community_controversy ON post_aggregates (featured_community DESC, controversy_rank DESC);
CREATE INDEX idx_comment_aggregates_controversy ON comment_aggregates (controversy_rank DESC);
-- Update post_aggregates_score trigger function to include controversy_rank update
CREATE OR REPLACE FUNCTION post_aggregates_score ()
RETURNS TRIGGER
LANGUAGE plpgsql
AS $$
BEGIN
IF (TG_OP = 'INSERT') THEN
UPDATE
post_aggregates pa
SET
score = score + NEW.score,
upvotes = CASE WHEN NEW.score = 1 THEN
upvotes + 1
ELSE
upvotes
END,
downvotes = CASE WHEN NEW.score = - 1 THEN
downvotes + 1
ELSE
downvotes
END,
controversy_rank = controversy_rank (pa.upvotes + CASE WHEN NEW.score = 1 THEN
1
ELSE
0
END::numeric, pa.downvotes + CASE WHEN NEW.score = - 1 THEN
1
ELSE
0
END::numeric)
WHERE
pa.post_id = NEW.post_id;
ELSIF (TG_OP = 'DELETE') THEN
-- Join to post because that post may not exist anymore
UPDATE
post_aggregates pa
SET
score = score - OLD.score,
upvotes = CASE WHEN OLD.score = 1 THEN
upvotes - 1
ELSE
upvotes
END,
downvotes = CASE WHEN OLD.score = - 1 THEN
downvotes - 1
ELSE
downvotes
END,
controversy_rank = controversy_rank (pa.upvotes + CASE WHEN NEW.score = 1 THEN
1
ELSE
0
END::numeric, pa.downvotes + CASE WHEN NEW.score = - 1 THEN
1
ELSE
0
END::numeric)
FROM
post p
WHERE
pa.post_id = p.id
AND pa.post_id = OLD.post_id;
END IF;
RETURN NULL;
END
$$;
-- Update comment_aggregates_score trigger function to include controversy_rank update
CREATE OR REPLACE FUNCTION comment_aggregates_score ()
RETURNS TRIGGER
LANGUAGE plpgsql
AS $$
BEGIN
IF (TG_OP = 'INSERT') THEN
UPDATE
comment_aggregates ca
SET
score = score + NEW.score,
upvotes = CASE WHEN NEW.score = 1 THEN
upvotes + 1
ELSE
upvotes
END,
downvotes = CASE WHEN NEW.score = - 1 THEN
downvotes + 1
ELSE
downvotes
END,
controversy_rank = controversy_rank (ca.upvotes + CASE WHEN NEW.score = 1 THEN
1
ELSE
0
END::numeric, ca.downvotes + CASE WHEN NEW.score = - 1 THEN
1
ELSE
0
END::numeric)
WHERE
ca.comment_id = NEW.comment_id;
ELSIF (TG_OP = 'DELETE') THEN
-- Join to comment because that comment may not exist anymore
UPDATE
comment_aggregates ca
SET
score = score - OLD.score,
upvotes = CASE WHEN OLD.score = 1 THEN
upvotes - 1
ELSE
upvotes
END,
downvotes = CASE WHEN OLD.score = - 1 THEN
downvotes - 1
ELSE
downvotes
END,
controversy_rank = controversy_rank (ca.upvotes + CASE WHEN NEW.score = 1 THEN
1
ELSE
0
END::numeric, ca.downvotes + CASE WHEN NEW.score = - 1 THEN
1
ELSE
0
END::numeric)
FROM
comment c
WHERE
ca.comment_id = c.id
AND ca.comment_id = OLD.comment_id;
END IF;
RETURN NULL;
END
$$;