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MySQL troubles
See original GitHub issueAs mentioned in #476 I still have massive CPU load when using Bookmarks v4.0.5, Floccus v4.4.6, Nextcloud v20.0.1 in combination with syncing floccus
Here are some database insights:
MariaDB [nextcloud]> EXPLAIN SELECT `b`.`id`, `b`.`url`, `b`.`title`, `b`.`description`, `b`.`lastmodified`, `b`.`added`, `b`.`clickcount`, `b`.`last_preview`, `b`.`available`, `b`.`archived_file`, `b`.`user_id`, GROUP_CONCAT(`tree`.`parent_folder`) AS `folders`, GROUP_CONCAT(`t`.`tag`) AS `tags` FROM `oc_bookmarks` `b` LEFT JOIN `oc_bookmarks_tree` `tree` ON (`b`.`id` = `tree`.`id`) AND (`tree`.`type` = 'bookmark') LEFT JOIN `oc_bookmarks_tags` `t` ON `t`.`bookmark_id` = `b`.`id` LEFT JOIN `oc_bookmarks_tree` `tr` ON (`tr`.`id` = `b`.`id`) AND (`tr`.`type` = 'bookmark') LEFT JOIN `oc_bookmarks_shared_folders` `sf` ON `tr`.`parent_folder` = `sf`.`folder_id` LEFT JOIN `oc_bookmarks_tree` `tr2` ON (`tr2`.`id` = `tr`.`parent_folder`) AND (`tr2`.`type` = 'folder') LEFT JOIN `oc_bookmarks_shared_folders` `sf2` ON `tr2`.`parent_folder` = `sf`.`folder_id` WHERE (`b`.`user_id` = 'fabi') OR (`sf`.`user_id` = 'fabi') OR (`sf2`.`user_id` = 'fabi') GROUP BY `b`.`id`, `b`.`url`, `b`.`title`, `b`.`description`, `b`.`lastmodified`, `b`.`added`, `b`.`clickcount`, `b`.`last_preview`, `b`.`available`, `b`.`archived_file`, `b`.`user_id`, `b`.`id` ORDER BY `b`.`lastmodified` DESC, `b`.`id` ASC LIMIT 300
-> ;
+------+-------------+-------+-------+-------------------------------------------+-----------------------+---------+----------------------------------+------+--------------------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-------+-------+-------------------------------------------+-----------------------+---------+----------------------------------+------+--------------------------------------------------------------+
| 1 | SIMPLE | b | ALL | IDX_3EE1CD04A76ED395,bookmarks_deadbyuser | NULL | NULL | NULL | 796 | Using temporary; Using filesort |
| 1 | SIMPLE | tree | ref | PRIMARY | PRIMARY | 90 | nextcloud.b.id,const | 1 | Using where; Using index |
| 1 | SIMPLE | t | ref | bookmark_tag | bookmark_tag | 9 | nextcloud.b.id | 1 | Using index |
| 1 | SIMPLE | tr | ref | PRIMARY | PRIMARY | 90 | nextcloud.b.id,const | 1 | Using where; Using index |
| 1 | SIMPLE | sf | ALL | bookmarks_shared_folder | NULL | NULL | NULL | 1 | Using where; Using join buffer (flat, BNL join) |
| 1 | SIMPLE | tr2 | ref | PRIMARY | PRIMARY | 90 | nextcloud.tr.parent_folder,const | 1 | Using where; Using index |
| 1 | SIMPLE | sf2 | index | NULL | bookmarks_shared_user | 1022 | NULL | 1 | Using where; Using index; Using join buffer (flat, BNL join) |
+------+-------------+-------+-------+-------------------------------------------+-----------------------+---------+----------------------------------+------+--------------------------------------------------------------+
MariaDB [nextcloud]> SHOW INDEX FROM oc_bookmarks;
+--------------+------------+----------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+--------------+------------+----------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| oc_bookmarks | 0 | PRIMARY | 1 | id | A | 796 | NULL | NULL | | BTREE | | |
| oc_bookmarks | 1 | IDX_3EE1CD04A76ED395 | 1 | user_id | A | 4 | NULL | NULL | | BTREE | | |
| oc_bookmarks | 1 | IDX_3EE1CD04DF091378 | 1 | last_preview | A | 2 | NULL | NULL | YES | BTREE | | |
| oc_bookmarks | 1 | bookmarks_modified | 1 | lastmodified | A | 796 | NULL | NULL | YES | BTREE | | |
| oc_bookmarks | 1 | bookmarks_deadbyuser | 1 | user_id | A | 4 | NULL | NULL | | BTREE | | |
| oc_bookmarks | 1 | bookmarks_deadbyuser | 2 | available | A | 4 | NULL | NULL | | BTREE | | |
| oc_bookmarks | 1 | bookmarks_dead | 1 | available | A | 2 | NULL | NULL | | BTREE | | |
+--------------+------------+----------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
MariaDB [nextcloud]> SHOW INDEX FROM oc_bookmarks_tree;
+-------------------+------------+-------------------------+--------------+---------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------------+------------+-------------------------+--------------+---------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| oc_bookmarks_tree | 0 | PRIMARY | 1 | id | A | 55116 | NULL | NULL | | BTREE | | |
| oc_bookmarks_tree | 0 | PRIMARY | 2 | type | A | 55116 | NULL | NULL | | BTREE | | |
| oc_bookmarks_tree | 0 | PRIMARY | 3 | parent_folder | A | 55116 | NULL | NULL | | BTREE | | |
| oc_bookmarks_tree | 1 | bookmarks_tree_parent | 1 | parent_folder | A | 27558 | NULL | NULL | | BTREE | | |
| oc_bookmarks_tree | 1 | bookmarks_tree_parent_i | 1 | parent_folder | A | 18372 | NULL | NULL | | BTREE | | |
| oc_bookmarks_tree | 1 | bookmarks_tree_parent_i | 2 | index | A | 55116 | NULL | NULL | | BTREE | | |
+-------------------+------------+-------------------------+--------------+---------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
6 rows in set (0.001 sec)
MariaDB [nextcloud]> SHOW INDEX FROM oc_bookmarks_tags;
+-------------------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| oc_bookmarks_tags | 0 | bookmark_tag | 1 | bookmark_id | A | 0 | NULL | NULL | YES | BTREE | | |
| oc_bookmarks_tags | 0 | bookmark_tag | 2 | tag | A | 0 | NULL | NULL | | BTREE | | |
+-------------------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
MariaDB [nextcloud]> SHOW INDEX FROM oc_bookmarks_shared_folders;
+-----------------------------+------------+-------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-----------------------------+------------+-------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| oc_bookmarks_shared_folders | 0 | PRIMARY | 1 | id | A | 0 | NULL | NULL | | BTREE | | |
| oc_bookmarks_shared_folders | 1 | bookmarks_shared_user | 1 | user_id | A | 0 | NULL | NULL | | BTREE | | |
| oc_bookmarks_shared_folders | 1 | bookmarks_shared_folder | 1 | folder_id | A | 0 | NULL | NULL | | BTREE | | |
+-----------------------------+------------+-------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
MariaDB [nextcloud]> SHOW variables like "%buffer%";
+-------------------------------------+----------------+
| Variable_name | Value |
+-------------------------------------+----------------+
| aria_pagecache_buffer_size | 134217728 |
| aria_sort_buffer_size | 268434432 |
| bulk_insert_buffer_size | 16777216 |
| innodb_buffer_pool_chunk_size | 134217728 |
| innodb_buffer_pool_dump_at_shutdown | ON |
| innodb_buffer_pool_dump_now | OFF |
| innodb_buffer_pool_dump_pct | 25 |
| innodb_buffer_pool_filename | ib_buffer_pool |
| innodb_buffer_pool_instances | 1 |
| innodb_buffer_pool_load_abort | OFF |
| innodb_buffer_pool_load_at_startup | ON |
| innodb_buffer_pool_load_now | OFF |
| innodb_buffer_pool_size | 1073741824 |
| innodb_change_buffer_max_size | 25 |
| innodb_change_buffering | all |
| innodb_log_buffer_size | 8388608 |
| innodb_sort_buffer_size | 1048576 |
| join_buffer_size | 262144 |
| join_buffer_space_limit | 2097152 |
| key_buffer_size | 134217728 |
| mrr_buffer_size | 262144 |
| myisam_sort_buffer_size | 536870912 |
| net_buffer_length | 16384 |
| preload_buffer_size | 32768 |
| read_buffer_size | 2097152 |
| read_rnd_buffer_size | 1048576 |
| sort_buffer_size | 4194304 |
| sql_buffer_result | OFF |
+-------------------------------------+----------------+
28 rows in set (0.003 sec)
MariaDB [nextcloud]> SHOW variables like "%table_size%";
+-----------------------+----------------------+
| Variable_name | Value |
+-----------------------+----------------------+
| max_heap_table_size | 33554432 |
| tmp_disk_table_size | 18446744073709551615 |
| tmp_memory_table_size | 33554432 |
| tmp_table_size | 33554432 |
+-----------------------+----------------------+
4 rows in set (0.001 sec)
_Originally posted by @faaaaabi in https://github.com/marcelklehr/floccus/issues/476#issuecomment-726923253_
Issue Analytics
- State:
- Created 3 years ago
- Comments:17 (11 by maintainers)
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the tree table should not grow much larger than the bookmarks table, except for cases where the same bookmark is in multiple folders. There is now a repair step that should get rid of all superfluous tree entries.
Hey there!
It’s been a while, but I’ve finally uncovered the reason for this peculiar behavior and will release a patch to the bookmarks app shortly: https://github.com/nextcloud/bookmarks/pull/1608
The problem was that the query in question needs to load all bookmarks in the db initially since they could all potentially be viewed by the current user (if they are shared with the current user, which however, will only be discovered after a JOIN). My solution, now, is to initially only load bookmarks by users that have shared bookmarks with the current user, which is still not ideal, but should be a much smaller set than ALL.