Investigate data size concerns for adding a new index to `solo_scores` about osu-infrastructure

[peppy]

Based on investigations above, the change in structure I'm looking to apply is:

--- old.sql	2023-09-01 18:17:38
+++ new.sql	2023-09-01 18:18:47
@@ -8,9 +8,9 @@
   `preserve` tinyint(1) NOT NULL DEFAULT '0',
   `created_at` datetime NOT NULL,
   `updated_at` timestamp NULL DEFAULT NULL,
-  PRIMARY KEY (`id`,`ruleset_id`,`preserve`,`created_at`),
-  KEY `user_ruleset_id_index` (`user_id`,`ruleset_id`,`id` DESC),
-  KEY `beatmap_id` (`beatmap_id`)
+  PRIMARY KEY (`id`,`preserve`,`created_at`),
+  KEY `user_ruleset_index` (`user_id`,`ruleset_id`),
+  KEY `beatmap_user_index` (`beatmap_id`,`user_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=4
 /*!50500 PARTITION BY RANGE  COLUMNS(`preserve`,created_at)
 (PARTITION p0catch VALUES LESS THAN (0,MAXVALUE) ENGINE = InnoDB,

• Index added to allow lookups of a user's scores on a specific beatmap (as required for ppy/osu-queue-score-statistics#149). Note that the order of this index keeps beatmap_id first to aid in operations on a whole beatmap (ie. deleting all scores).
• id DESC removed from user_ruleset_index – it's not required as it's in the primary key and implicitly available at the end of the index. This doesn't reduce the index size, so MySQL was likely doing this optimisation internally.
• Removed ruleset_id from primary key. It wasn't being used and will not be used in partitioning scheme due to extensibility concerns (see OP for more commentary).

This is a first checkpoint, I still have some further smaller changes to test:

TODO:

• Consider changing partitioning to be on updated_at instead of created_id (see concerns in #16)
• Change created_at to timestamp (saving 4 bytes per row)
• Add default value for created_at and updated_at
• Make updated_at NOT NULL

[peppy]

Updated with TODO changes applied:

--- old.sql	2023-09-01 18:17:38
+++ new.sql	2023-09-01 20:03:04
@@ -6,12 +6,12 @@
   `data` json NOT NULL,
   `has_replay` tinyint(1) DEFAULT '0',
   `preserve` tinyint(1) NOT NULL DEFAULT '0',
-  `created_at` datetime NOT NULL,
-  `updated_at` timestamp NULL DEFAULT NULL,
-  PRIMARY KEY (`id`,`ruleset_id`,`preserve`,`created_at`),
-  KEY `user_ruleset_id_index` (`user_id`,`ruleset_id`,`id` DESC),
-  KEY `beatmap_id` (`beatmap_id`)
+  `created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  `updated_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+  PRIMARY KEY (`id`,`preserve`,`updated_at`),
+  KEY `user_ruleset_index` (`user_id`,`ruleset_id`),
+  KEY `beatmap_user_index` (`beatmap_id`,`user_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=4
-/*!50500 PARTITION BY RANGE  COLUMNS(`preserve`,created_at)
+/*!50500 PARTITION BY RANGE COLUMNS(`preserve`,`updated_at`)
 (PARTITION p0catch VALUES LESS THAN (0,MAXVALUE) ENGINE = InnoDB,
  PARTITION p1 VALUES LESS THAN (MAXVALUE,MAXVALUE) ENGINE = InnoDB) */

[peppy]

Bonus round: compression testing to ensure we have things fine tuned

Compression testing

Time values are from ALTER. In general this seems very optimised, so the actual overheads for INSERT etc. operations would be higher.

# key_size=16
# Time: 268.081s
-rw-r-----  1 dean  admin  6069157888 Sep  4 12:35 solo_scores_p#p#p0catch.ibd
-rw-r-----  1 dean  admin  3179282432 Sep  4 12:35 solo_scores_p#p#p1.ibd

# key_size=8
# Time: 195.931s

-rw-r-----  1 dean  admin  3036676096 Sep  4 11:33 solo_scores_p#p#p0catch.ibd
-rw-r-----  1 dean  admin  1598029824 Sep  4 11:33 solo_scores_p#p#p1.ibd

# key_size=4
# Time: 204.383s

-rw-r-----  1 dean  admin  1606418432 Sep  4 12:20 solo_scores_p#p#p0catch.ibd
-rw-r-----  1 dean  admin   872415232 Sep  4 12:20 solo_scores_p#p#p1.ibd

# key_size=2
# Time: 249.902s

-rw-r-----  1 dean  admin  1602224128 Sep  4 12:24 solo_scores_p#p#p0catch.ibd
-rw-r-----  1 dean  admin  1019215872 Sep  4 12:24 solo_scores_p#p#p1.ibd

# row_format=compact
# Time: 122.149s

-rw-r-----  1 dean  admin  6069157888 Sep  4 12:35 solo_scores_p#p#p0catch.ibd
-rw-r-----  1 dean  admin  3179282432 Sep  4 12:35 solo_scores_p#p#p1.ibd

# row_format=dynamic
# Time: 58.805s

-rw-r-----  1 dean  admin  6480199680 Sep  4 12:42 solo_scores_p#p#p0catch.ibd
-rw-r-----  1 dean  admin  3376414720 Sep  4 12:42 solo_scores_p#p#p1.ibd