Trying some DB indexes.

server/.gitignore

@@ -2,3 +2,4 @@
 .env
 .idea
 env_setup.sh
+query_testing/*.json

server/migrations/2020-01-11-012452_add_indexes/down.sql

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+-- This file should undo anything in `up.sql`
+
+drop index idx_post_creator;
+drop index idx_post_community;
+
+drop index idx_post_like_post;
+drop index idx_post_like_user;
+
+drop index idx_comment_creator;
+drop index idx_comment_parent;
+drop index idx_comment_post;
+
+drop index idx_comment_like_comment;
+drop index idx_comment_like_user;
+drop index idx_comment_like_post;
+
+drop index idx_community_creator;
+drop index idx_community_category;
+
+drop index idx_community_follower_community;
+drop index idx_community_follower_user;
+
+drop index idx_community_user_ban_community;
+drop index idx_community_user_ban_user;
+
+drop view post_view;
+create view post_view as
+with all_post as
+(
+  select        
+  p.*,
+  (select u.banned from user_ u where p.creator_id = u.id) as banned,
+  (select cb.id::bool from community_user_ban cb where p.creator_id = cb.user_id and p.community_id = cb.community_id) as banned_from_community,
+  (select name from user_ where p.creator_id = user_.id) as creator_name,
+  (select avatar from user_ where p.creator_id = user_.id) as creator_avatar,
+  (select name from community where p.community_id = community.id) as community_name,
+  (select removed from community c where p.community_id = c.id) as community_removed,
+  (select deleted from community c where p.community_id = c.id) as community_deleted,
+  (select nsfw from community c where p.community_id = c.id) as community_nsfw,
+  (select count(*) from comment where comment.post_id = p.id) as number_of_comments,
+  coalesce(sum(pl.score), 0) as score,
+  count (case when pl.score = 1 then 1 else null end) as upvotes,
+  count (case when pl.score = -1 then 1 else null end) as downvotes,
+  hot_rank(coalesce(sum(pl.score) , 0), p.published) as hot_rank
+  from post p
+  left join post_like pl on p.id = pl.post_id
+  group by p.id
+)
+
+select
+ap.*,
+u.id as user_id,
+coalesce(pl.score, 0) as my_vote,
+(select cf.id::bool from community_follower cf where u.id = cf.user_id and cf.community_id = ap.community_id) as subscribed,
+(select pr.id::bool from post_read pr where u.id = pr.user_id and pr.post_id = ap.id) as read,
+(select ps.id::bool from post_saved ps where u.id = ps.user_id and ps.post_id = ap.id) as saved
+from user_ u
+cross join all_post ap
+left join post_like pl on u.id = pl.user_id and ap.id = pl.post_id
+
+union all
+
+select 
+ap.*,
+null as user_id,
+null as my_vote,
+null as subscribed,
+null as read,
+null as saved
+from all_post ap
+;
+
+

server/migrations/2020-01-11-012452_add_indexes/up.sql

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+-- Go through all the tables joins, optimize every view, CTE, etc.
+
+create index idx_post_creator on post (creator_id);
+create index idx_post_community on post (community_id);
+
+create index idx_post_like_post on post_like (post_id);
+create index idx_post_like_user on post_like (user_id);
+
+create index idx_comment_creator on comment (creator_id);
+create index idx_comment_parent on comment (parent_id);
+create index idx_comment_post on comment (post_id);
+
+create index idx_comment_like_comment on comment_like (comment_id);
+create index idx_comment_like_user on comment_like (user_id);
+create index idx_comment_like_post on comment_like (post_id);
+
+create index idx_community_creator on community (creator_id);
+create index idx_community_category on community (category_id);
+
+create index idx_community_follower_community on community_follower (community_id);
+create index idx_community_follower_user on community_follower (user_id);
+
+create index idx_community_user_ban_community on community_user_ban (community_id);
+create index idx_community_user_ban_user on community_user_ban (user_id);
+
+-- optimize post_view
+
+drop view post_view;
+create view post_view as
+with all_post as
+(
+  select        
+  p.*,
+  u.banned as banned,
+  (select cb.id::bool from community_user_ban cb where p.creator_id = cb.user_id and p.community_id = cb.community_id) as banned_from_community,
+  u.name as creator_name, 
+  u.avatar as creator_avatar,
+  c.name as community_name, 
+  c.removed as community_removed,
+  c.deleted as community_deleted,
+  c.nsfw as community_nsfw,
+  (select count(*) from comment where comment.post_id = p.id) as number_of_comments,
+  coalesce(sum(pl.score), 0) as score,
+  count (case when pl.score = 1 then 1 else null end) as upvotes,
+  count (case when pl.score = -1 then 1 else null end) as downvotes,
+  hot_rank(coalesce(sum(pl.score) , 0), p.published) as hot_rank
+  from post p
+  left join post_like pl on p.id = pl.post_id
+  inner join user_ u on p.creator_id = u.id
+  inner join community c on p.community_id = c.id
+  group by p.id, u.banned, u.name, u.avatar, c.name, c.removed, c.deleted, c.nsfw
+)
+
+select
+ap.*,
+u.id as user_id,
+coalesce(pl.score, 0) as my_vote,
+(select cf.id::bool from community_follower cf where u.id = cf.user_id and cf.community_id = ap.community_id) as subscribed,
+(select pr.id::bool from post_read pr where u.id = pr.user_id and pr.post_id = ap.id) as read,
+(select ps.id::bool from post_saved ps where u.id = ps.user_id and ps.post_id = ap.id) as saved
+from user_ u
+cross join all_post ap
+left join post_like pl on u.id = pl.user_id and ap.id = pl.post_id
+
+union all
+
+select 
+ap.*,
+null as user_id,
+null as my_vote,
+null as subscribed,
+null as read,
+null as saved
+from all_post ap
+;

server/query_testing/generate_explain_reports.sh

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+#!/bin/sh
+
+# Do the views first
+
+echo "explain (analyze, format json) select * from user_view" > explain.sql
+psql -qAt -U lemmy -f explain.sql > user_view.json
+
+echo "explain (analyze, format json) select * from post_view where user_id is null order by hot_rank desc" > explain.sql
+psql -qAt -U lemmy -f explain.sql > post_view.json
+
+echo "explain (analyze, format json) select * from comment_view where user_id is null" > explain.sql
+psql -qAt -U lemmy -f explain.sql > comment_view.json
+
+echo "explain (analyze, format json) select * from community_view where user_id is null order by hot_rank desc" > explain.sql
+psql -qAt -U lemmy -f explain.sql > community_view.json
+
+grep "Execution Time" *.json
+
+rm explain.sql