Update community statistics after post or comment is deleted by user (#2193)

* Update community statistics after post or comment is deleted by user

* Update triggers for site and person aggregates

* Restore comment counts when post is restored

* Simplify insertion/deletion trigger checks before updating statistics

diff --git a/migrations/2022-04-04-183652_update_community_aggregates_on_soft_delete/down.sql b/migrations/2022-04-04-183652_update_community_aggregates_on_soft_delete/down.sql
new file mode 100644 (file)
index 0000000..8a8ea5c
--- /dev/null
+++ b/migrations/2022-04-04-183652_update_community_aggregates_on_soft_delete/down.sql
@@ -0,0 +1,254 @@
+drop trigger if exists community_aggregates_post_count on post;
+drop trigger if exists community_aggregates_comment_count on comment;
+drop trigger if exists site_aggregates_comment_insert on comment;
+drop trigger if exists site_aggregates_comment_delete on comment;
+drop trigger if exists site_aggregates_post_insert on post;
+drop trigger if exists site_aggregates_post_delete on post;
+drop trigger if exists site_aggregates_community_insert on community;
+drop trigger if exists site_aggregates_community_delete on community;
+drop trigger if exists person_aggregates_post_count on post;
+drop trigger if exists person_aggregates_comment_count on comment;
+
+drop function was_removed_or_deleted(TG_OP text, OLD record, NEW record);
+drop function was_restored_or_created(TG_OP text, OLD record, NEW record);
+
+-- Community aggregate functions
+
+create or replace function community_aggregates_post_count()
+    returns trigger language plpgsql
+as $$
+begin
+  IF (TG_OP = 'INSERT') THEN
+update community_aggregates
+set posts = posts + 1 where community_id = NEW.community_id;
+ELSIF (TG_OP = 'DELETE') THEN
+update community_aggregates
+set posts = posts - 1 where community_id = OLD.community_id;
+
+-- Update the counts if the post got deleted
+update community_aggregates ca
+set posts = coalesce(cd.posts, 0),
+    comments = coalesce(cd.comments, 0)
+    from ( 
+      select 
+      c.id,
+      count(distinct p.id) as posts,
+      count(distinct ct.id) as comments
+      from community c
+      left join post p on c.id = p.community_id
+      left join comment ct on p.id = ct.post_id
+      group by c.id
+    ) cd
+where ca.community_id = OLD.community_id;
+END IF;
+return null;
+end $$;
+
+create or replace function community_aggregates_comment_count()
+    returns trigger language plpgsql
+as $$
+begin
+  IF (TG_OP = 'INSERT') THEN
+update community_aggregates ca
+set comments = comments + 1 from comment c, post p
+where p.id = c.post_id
+  and p.id = NEW.post_id
+  and ca.community_id = p.community_id;
+ELSIF (TG_OP = 'DELETE') THEN
+update community_aggregates ca
+set comments = comments - 1 from comment c, post p
+where p.id = c.post_id
+  and p.id = OLD.post_id
+  and ca.community_id = p.community_id;
+
+END IF;
+return null;
+end $$;
+
+-- Community aggregate triggers
+
+create trigger community_aggregates_post_count
+    after insert or delete on post
+for each row
+execute procedure community_aggregates_post_count();
+
+create trigger community_aggregates_comment_count
+    after insert or delete on comment
+for each row
+execute procedure community_aggregates_comment_count();
+
+-- Site aggregate functions
+
+create or replace function site_aggregates_post_insert()
+    returns trigger language plpgsql
+as $$
+begin
+update site_aggregates
+set posts = posts + 1;
+return null;
+end $$;
+
+create or replace function site_aggregates_post_delete()
+    returns trigger language plpgsql
+as $$
+begin
+update site_aggregates sa
+set posts = posts - 1
+    from site s
+where sa.site_id = s.id;
+return null;
+end $$;
+
+create or replace function site_aggregates_comment_insert()
+    returns trigger language plpgsql
+as $$
+begin
+update site_aggregates
+set comments = comments + 1;
+return null;
+end $$;
+
+create or replace function site_aggregates_comment_delete()
+    returns trigger language plpgsql
+as $$
+begin
+update site_aggregates sa
+set comments = comments - 1
+    from site s
+where sa.site_id = s.id;
+return null;
+end $$;
+
+create or replace function site_aggregates_community_insert()
+    returns trigger language plpgsql
+as $$
+begin
+update site_aggregates
+set communities = communities + 1;
+return null;
+end $$;
+
+create or replace function site_aggregates_community_delete()
+    returns trigger language plpgsql
+as $$
+begin
+update site_aggregates sa
+set communities = communities - 1
+    from site s
+where sa.site_id = s.id;
+return null;
+end $$;
+
+
+-- Site update triggers
+
+create trigger site_aggregates_post_insert
+    after insert on post
+    for each row
+    when (NEW.local = true)
+    execute procedure site_aggregates_post_insert();
+
+create trigger site_aggregates_post_delete
+    after delete on post
+    for each row
+    when (OLD.local = true)
+    execute procedure site_aggregates_post_delete();
+
+create trigger site_aggregates_comment_insert
+    after insert on comment
+    for each row
+    when (NEW.local = true)
+    execute procedure site_aggregates_comment_insert();
+
+create trigger site_aggregates_comment_delete
+    after delete on comment
+    for each row
+    when (OLD.local = true)
+    execute procedure site_aggregates_comment_delete();
+
+create trigger site_aggregates_community_insert
+    after insert on community
+    for each row
+    when (NEW.local = true)
+    execute procedure site_aggregates_community_insert();
+
+create trigger site_aggregates_community_delete
+    after delete on community
+    for each row
+    when (OLD.local = true)
+    execute procedure site_aggregates_community_delete();
+
+-- Person aggregate functions
+
+create or replace function person_aggregates_post_count()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (TG_OP = 'INSERT') THEN
+update person_aggregates
+set post_count = post_count + 1 where person_id = NEW.creator_id;
+
+ELSIF (TG_OP = 'DELETE') THEN
+update person_aggregates
+set post_count = post_count - 1 where person_id = OLD.creator_id;
+
+-- If the post gets deleted, the score calculation trigger won't fire,
+-- so you need to re-calculate
+update person_aggregates ua
+set post_score = pd.score
+    from (
+                 select u.id,
+                        coalesce(0, sum(pl.score)) as score
+                        -- User join because posts could be empty
+                 from person u
+                          left join post p on u.id = p.creator_id
+                          left join post_like pl on p.id = pl.post_id
+                 group by u.id
+             ) pd
+where ua.person_id = OLD.creator_id;
+
+END IF;
+return null;
+end $$;
+
+create or replace function person_aggregates_comment_count()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (TG_OP = 'INSERT') THEN
+update person_aggregates
+set comment_count = comment_count + 1 where person_id = NEW.creator_id;
+ELSIF (TG_OP = 'DELETE') THEN
+update person_aggregates
+set comment_count = comment_count - 1 where person_id = OLD.creator_id;
+
+-- If the comment gets deleted, the score calculation trigger won't fire,
+-- so you need to re-calculate
+update person_aggregates ua
+set comment_score = cd.score
+    from (
+                 select u.id,
+                        coalesce(0, sum(cl.score)) as score
+                        -- User join because comments could be empty
+                 from person u
+                          left join comment c on u.id = c.creator_id
+                          left join comment_like cl on c.id = cl.comment_id
+                 group by u.id
+             ) cd
+where ua.person_id = OLD.creator_id;
+END IF;
+return null;
+end $$;
+
+
+-- Person aggregate triggers
+
+create trigger person_aggregates_post_count
+    after insert or delete on post
+    for each row
+execute procedure person_aggregates_post_count();
+
+create trigger person_aggregates_comment_count
+    after insert or delete on comment
+    for each row
+execute procedure person_aggregates_comment_count();
\ No newline at end of file

diff --git a/migrations/2022-04-04-183652_update_community_aggregates_on_soft_delete/up.sql b/migrations/2022-04-04-183652_update_community_aggregates_on_soft_delete/up.sql
new file mode 100644 (file)
index 0000000..472be54
--- /dev/null
+++ b/migrations/2022-04-04-183652_update_community_aggregates_on_soft_delete/up.sql
@@ -0,0 +1,327 @@
+drop trigger if exists community_aggregates_post_count on post;
+drop trigger if exists community_aggregates_comment_count on comment;
+drop trigger if exists site_aggregates_comment_insert on comment;
+drop trigger if exists site_aggregates_comment_delete on comment;
+drop trigger if exists site_aggregates_post_insert on post;
+drop trigger if exists site_aggregates_post_delete on post;
+drop trigger if exists site_aggregates_community_insert on community;
+drop trigger if exists site_aggregates_community_delete on community;
+drop trigger if exists person_aggregates_post_count on post;
+drop trigger if exists person_aggregates_comment_count on comment;
+
+create or replace function was_removed_or_deleted(TG_OP text, OLD record, NEW record)
+RETURNS boolean
+LANGUAGE plpgsql
+as $$
+    begin
+        IF (TG_OP = 'INSERT') THEN
+            return false;
+        end if;
+
+        IF (TG_OP = 'DELETE') THEN
+            return true;
+        end if;
+
+    return TG_OP = 'UPDATE' AND (
+            (OLD.deleted = 'f' AND NEW.deleted = 't') OR
+            (OLD.removed = 'f' AND NEW.removed = 't')
+            );
+END $$;
+
+create or replace function was_restored_or_created(TG_OP text, OLD record, NEW record)
+    RETURNS boolean
+    LANGUAGE plpgsql
+as $$
+begin
+    IF (TG_OP = 'DELETE') THEN
+        return false;
+    end if;
+
+    IF (TG_OP = 'INSERT') THEN
+        return true;
+    end if;
+
+   return TG_OP = 'UPDATE' AND (
+        (OLD.deleted = 't' AND NEW.deleted = 'f') OR
+        (OLD.removed = 't' AND NEW.removed = 'f')
+        );
+END $$;
+
+-- Community aggregate functions
+
+create or replace function community_aggregates_post_count()
+    returns trigger language plpgsql
+as $$
+begin
+  IF (was_restored_or_created(TG_OP, OLD, NEW)) THEN
+update community_aggregates
+set posts = posts + 1 where community_id = NEW.community_id;
+
+IF (TG_OP = 'UPDATE') THEN
+    -- Post was restored, so restore comment counts as well
+    update community_aggregates ca
+    set posts = coalesce(cd.posts, 0),
+        comments = coalesce(cd.comments, 0)
+    from (
+             select
+                 c.id,
+                 count(distinct p.id) as posts,
+                 count(distinct ct.id) as comments
+             from community c
+                      left join post p on c.id = p.community_id and p.deleted = 'f' and p.removed = 'f'
+                      left join comment ct on p.id = ct.post_id and ct.deleted = 'f' and ct.removed = 'f'
+             where c.id = NEW.community_id
+             group by c.id
+         ) cd
+    where ca.community_id = NEW.community_id;
+END IF;
+
+ELSIF (was_removed_or_deleted(TG_OP, OLD, NEW)) THEN
+update community_aggregates
+set posts = posts - 1 where community_id = OLD.community_id;
+
+-- Update the counts if the post got deleted
+update community_aggregates ca
+set posts = coalesce(cd.posts, 0),
+    comments = coalesce(cd.comments, 0)
+    from ( 
+      select 
+      c.id,
+      count(distinct p.id) as posts,
+      count(distinct ct.id) as comments
+      from community c
+      left join post p on c.id = p.community_id and p.deleted = 'f' and p.removed = 'f'
+      left join comment ct on p.id = ct.post_id and ct.deleted = 'f' and ct.removed = 'f'
+      where c.id = OLD.community_id
+      group by c.id
+    ) cd
+where ca.community_id = OLD.community_id;
+END IF;
+return null;
+end $$;
+
+-- comment count
+create or replace function community_aggregates_comment_count()
+    returns trigger language plpgsql
+as $$
+begin
+  IF (was_restored_or_created(TG_OP, OLD, NEW)) THEN
+update community_aggregates ca
+set comments = comments + 1 from comment c, post p
+where p.id = c.post_id
+  and p.id = NEW.post_id
+  and ca.community_id = p.community_id;
+ELSIF (was_removed_or_deleted(TG_OP, OLD, NEW)) THEN
+update community_aggregates ca
+set comments = comments - 1 from comment c, post p
+where p.id = c.post_id
+  and p.id = OLD.post_id
+  and ca.community_id = p.community_id;
+
+END IF;
+return null;
+end $$;
+
+-- Community aggregate triggers
+
+create trigger community_aggregates_post_count
+    after insert or delete or update of removed, deleted on post
+    for each row
+execute procedure community_aggregates_post_count();
+
+create trigger community_aggregates_comment_count
+    after insert or delete or update of removed, deleted on comment
+for each row
+execute procedure community_aggregates_comment_count();
+
+-- Site aggregate functions
+
+create or replace function site_aggregates_post_insert()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (was_restored_or_created(TG_OP, OLD, NEW)) THEN
+        update site_aggregates sa
+        set posts = posts + 1
+        from site s
+        where sa.site_id = s.id;
+    END IF;
+    return null;
+end $$;
+
+create or replace function site_aggregates_post_delete()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (was_removed_or_deleted(TG_OP, OLD, NEW)) THEN
+        update site_aggregates sa
+        set posts = posts - 1
+        from site s
+        where sa.site_id = s.id;
+    END IF;
+    return null;
+end $$;
+
+create or replace function site_aggregates_comment_insert()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (was_restored_or_created(TG_OP, OLD, NEW)) THEN
+        update site_aggregates sa
+        set comments = comments + 1
+        from site s
+        where sa.site_id = s.id;
+    END IF;
+    return null;
+end $$;
+
+create or replace function site_aggregates_comment_delete()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (was_removed_or_deleted(TG_OP, OLD, NEW)) THEN
+        update site_aggregates sa
+        set comments = comments - 1
+        from site s
+        where sa.site_id = s.id;
+    END IF;
+    return null;
+end $$;
+
+create or replace function site_aggregates_community_insert()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (was_restored_or_created(TG_OP, OLD, NEW)) THEN
+        update site_aggregates sa
+        set communities = communities + 1
+        from site s
+        where sa.site_id = s.id;
+    END IF;
+    return null;
+end $$;
+
+create or replace function site_aggregates_community_delete()
+    returns trigger language plpgsql
+as $$
+begin
+        IF (was_removed_or_deleted(TG_OP, OLD, NEW)) THEN
+        update site_aggregates sa
+        set communities = communities - 1
+        from site s
+        where sa.site_id = s.id;
+    END IF;
+    return null;
+end $$;
+
+-- Site aggregate triggers
+
+create trigger site_aggregates_post_insert
+    after insert or update of removed, deleted on post
+    for each row
+    when (NEW.local = true)
+execute procedure site_aggregates_post_insert();
+
+create trigger site_aggregates_post_delete
+    after delete or update of removed, deleted on post
+    for each row
+    when (OLD.local = true)
+execute procedure site_aggregates_post_delete();
+
+create trigger site_aggregates_comment_insert
+    after insert or update of removed, deleted on comment
+    for each row
+    when (NEW.local = true)
+execute procedure site_aggregates_comment_insert();
+
+create trigger site_aggregates_comment_delete
+    after delete or update of removed, deleted on comment
+    for each row
+    when (OLD.local = true)
+execute procedure site_aggregates_comment_delete();
+
+create trigger site_aggregates_community_insert
+    after insert or update of removed, deleted on community
+    for each row
+    when (NEW.local = true)
+execute procedure site_aggregates_community_insert();
+
+create trigger site_aggregates_community_delete
+    after delete or update of removed, deleted on community
+    for each row
+    when (OLD.local = true)
+execute procedure site_aggregates_community_delete();
+
+-- Person aggregate functions
+
+create or replace function person_aggregates_post_count()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (was_restored_or_created(TG_OP, OLD, NEW)) THEN
+        update person_aggregates
+        set post_count = post_count + 1 where person_id = NEW.creator_id;
+
+    ELSIF (was_removed_or_deleted(TG_OP, OLD, NEW)) THEN
+        update person_aggregates
+        set post_count = post_count - 1 where person_id = OLD.creator_id;
+
+        -- If the post gets deleted, the score calculation trigger won't fire,
+        -- so you need to re-calculate
+        update person_aggregates ua
+        set post_score = pd.score
+        from (
+                 select u.id,
+                        coalesce(0, sum(pl.score)) as score
+                        -- User join because posts could be empty
+                 from person u
+                          left join post p on u.id = p.creator_id and p.deleted = 'f' and p.removed = 'f'
+                          left join post_like pl on p.id = pl.post_id
+                 group by u.id
+             ) pd
+        where ua.person_id = OLD.creator_id;
+
+    END IF;
+    return null;
+end $$;
+
+create or replace function person_aggregates_comment_count()
+    returns trigger language plpgsql
+as $$
+begin
+    IF (was_restored_or_created(TG_OP, OLD, NEW)) THEN
+        update person_aggregates
+        set comment_count = comment_count + 1 where person_id = NEW.creator_id;
+    ELSIF (was_removed_or_deleted(TG_OP, OLD, NEW)) THEN
+        update person_aggregates
+        set comment_count = comment_count - 1 where person_id = OLD.creator_id;
+
+        -- If the comment gets deleted, the score calculation trigger won't fire,
+        -- so you need to re-calculate
+        update person_aggregates ua
+        set comment_score = cd.score
+        from (
+                 select u.id,
+                        coalesce(0, sum(cl.score)) as score
+                        -- User join because comments could be empty
+                 from person u
+                          left join comment c on u.id = c.creator_id and c.deleted = 'f' and c.removed = 'f'
+                          left join comment_like cl on c.id = cl.comment_id
+                 group by u.id
+             ) cd
+        where ua.person_id = OLD.creator_id;
+    END IF;
+    return null;
+end $$;
+
+-- Person aggregate triggers
+
+create trigger person_aggregates_post_count
+    after insert or delete or update of removed, deleted on post
+    for each row
+execute procedure person_aggregates_post_count();
+
+create trigger person_aggregates_comment_count
+    after insert or delete or update of removed, deleted on comment
+    for each row
+execute procedure person_aggregates_comment_count();