Fixing slow joins to post_read, post_saved, and comment_saved . (#2738)

- Fixes #2445

crates/db_views/src/comment_view.rs

@@ -311,7 +311,7 @@ impl<'a> CommentQuery<'a> {
     }
 
     if self.saved_only.unwrap_or(false) {
-      query = query.filter(comment_saved::id.is_not_null());
+      query = query.filter(comment_saved::comment_id.is_not_null());
     }
 
     if !self.show_deleted_and_removed.unwrap_or(true) {
@@ -325,7 +325,7 @@ impl<'a> CommentQuery<'a> {
 
     if self.local_user.is_some() {
       // Filter out the rows with missing languages
-      query = query.filter(local_user_language::id.is_not_null());
+      query = query.filter(local_user_language::language_id.is_not_null());
 
       // Don't show blocked communities or persons
       query = query.filter(community_block::person_id.is_null());

crates/db_views/src/post_view.rs

@@ -365,17 +365,17 @@ impl<'a> PostQuery<'a> {
     };
 
     if self.saved_only.unwrap_or(false) {
-      query = query.filter(post_saved::id.is_not_null());
+      query = query.filter(post_saved::post_id.is_not_null());
     }
     // Only hide the read posts, if the saved_only is false. Otherwise ppl with the hide_read
     // setting wont be able to see saved posts.
     else if !self.local_user.map(|l| l.show_read_posts).unwrap_or(true) {
-      query = query.filter(post_read::id.is_null());
+      query = query.filter(post_read::post_id.is_null());
     }
 
     if self.local_user.is_some() {
       // Filter out the rows with missing languages
-      query = query.filter(local_user_language::id.is_not_null());
+      query = query.filter(local_user_language::language_id.is_not_null());
 
       // Don't show blocked communities or persons
       query = query.filter(community_block::person_id.is_null());

docker/docker-compose.yml

@@ -99,7 +99,8 @@ services:
       "postgres",
       "-c", "session_preload_libraries=auto_explain",
       "-c", "auto_explain.log_min_duration=5ms",
-      "-c", "auto_explain.log_analyze=true"
+      "-c", "auto_explain.log_analyze=true",
+      "-c", "track_activity_query_size=1048576"
     ]
     networks:
       - lemmyinternal

migrations/2023-02-15-212546_add_post_comment_saved_indexes/down.sql

@@ -0,0 +1 @@
+drop index idx_post_saved_person_id, idx_comment_saved_person_id;

migrations/2023-02-15-212546_add_post_comment_saved_indexes/up.sql

@@ -0,0 +1,2 @@
+create index idx_post_saved_person_id on post_saved (person_id);
+create index idx_comment_saved_person_id on comment_saved (person_id);