Mariadb 2 解释计划：使用连接缓冲区和不使用连接缓冲区
Mariadb 2 explains plan : with Using join buffer and without
我 运行 在具有巨大性能差异的 2 个环境中进行相同的查询：0.015 秒与 25 秒。
解释计划：
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------+------+----------+---------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------+------+----------+---------------------------------+
| 1 | SIMPLE | company1_ | const | PRIMARY | PRIMARY | 152 | const | 1 | 100.00 | Using temporary; Using filesort |
| 1 | SIMPLE | user2_ | ref | PRIMARY | PRIMARY | 152 | const | 1032 | 100.00 | Using where |
| 1 | SIMPLE | vacationpr5_ | eq_ref | PRIMARY | PRIMARY | 304 | user2_.ID_COMPANY_VACATION_PROFILE,.user2_.ID_VACATION_PROFILE | 1 | 100.00 | Using index |
| 1 | SIMPLE | vacationac0_ | ref | PRIMARY,I_VACATION_ACCUMULATION_EA | PRIMARY | 304 | const,.user2_.ID_USER | 4 | 100.00 | Using where |
| 1 | SIMPLE | vacationty3_ | eq_ref | PRIMARY | PRIMARY | 304 | const,.vacationac0_.ID_VACATION_TYPE | 1 | 100.00 | Using where |
| 1 | SIMPLE | vacationst6_ | eq_ref | PRIMARY | PRIMARY | 608 | user2_.ID_COMPANY_VACATION_PROFILE,.user2_.ID_VACATION_PROFILE,const,.vacationac0_.ID_VACATION_TYPE | 1 | 100.00 | Using where |
| 1 | SIMPLE | translatio9_ | eq_ref | PRIMARY | PRIMARY | 919 | vacationty3_.ID_COMPANY_TRANSLATION,.vacationty3_.ID_TRANSLATION | 1 | 100.00 | Using index |
| 1 | SIMPLE | descriptio10_ | eq_ref | PRIMARY, | PRIMARY | 951 | vacationty3_.ID_COMPANY_TRANSLATION,.vacationty3_.ID_TRANSLATION,const | 1 | 100.00 | Using where |
| 1 | SIMPLE | listvalue4_ | ALL | NULL | NULL | NULL | NULL | 5284 | 100.00 | Using where |
| 1 | SIMPLE | translatio7_ | eq_ref | PRIMARY | PRIMARY | 919 | listvalue4_.ID_COMPANY_TRANSLATION,.listvalue4_.ID_TRANSLATION | 1 | 100.00 | Using index |
| 1 | SIMPLE | descriptio8_ | eq_ref | PRIMARY | PRIMARY | 951 | listvalue4_.ID_COMPANY_TRANSLATION,.listvalue4_.ID_TRANSLATION,const | 1 | 100.00 | Using where |
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------+------+----------+---------------------------------+
接下来的讲解计划：
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------------------+------+----------+-------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------------------+------+----------+-------------------------------------------------+
| 1 | SIMPLE | company1_ | const | PRIMARY | PRIMARY | 152 | const | 1 | 100.00 | Using temporary; Using filesort |
| 1 | SIMPLE | user2_ | ref | PRIMARY, | PRIMARY | 152 | const | 1050 | 100.00 | Using where |
| 1 | SIMPLE | vacationpr5_ | eq_ref | PRIMARY | PRIMARY | 304 | validation2.user2_.ID_COMPANY_VACATION_PROFILE,validation2.user2_.ID_VACATION_PROFILE | 1 | 100.00 | Using index |
| 1 | SIMPLE | vacationac0_ | ref | PRIMARY,I_VACATION_ACCUMULATION_EA | PRIMARY | 304 | const,validation2.user2_.ID_USER | 5 | 100.00 | Using where |
| 1 | SIMPLE | vacationty3_ | eq_ref | PRIMARY | PRIMARY | 304 | const,validation2.vacationac0_.ID_VACATION_TYPE | 1 | 100.00 | Using where |
| 1 | SIMPLE | vacationst6_ | eq_ref | PRIMARY | PRIMARY | 608 | validation2.user2_.ID_COMPANY_VACATION_PROFILE,validation2.user2_.ID_VACATION_PROFILE,const,validation2.vacationac0_.ID_VACATION_TYPE | 1 | 100.00 | Using where |
| 1 | SIMPLE | translatio9_ | eq_ref | PRIMARY | PRIMARY | 919 | validation2.vacationty3_.ID_COMPANY_TRANSLATION,validation2.vacationty3_.ID_TRANSLATION | 1 | 100.00 | Using index |
| 1 | SIMPLE | descriptio10_ | eq_ref | PRIMARY, | PRIMARY | 951 | validation2.vacationty3_.ID_COMPANY_TRANSLATION,validation2.vacationty3_.ID_TRANSLATION,const | 1 | 100.00 | Using where |
| 1 | SIMPLE | listvalue4_ | ALL | NULL | NULL | NULL | NULL | 5282 | 100.00 | Using where; Using join buffer (flat, BNL join) |
| 1 | SIMPLE | translatio7_ | eq_ref | PRIMARY | PRIMARY | 919 | validation2.listvalue4_.ID_COMPANY_TRANSLATION,validation2.listvalue4_.ID_TRANSLATION | 1 | 100.00 | Using index |
| 1 | SIMPLE | descriptio8_ | eq_ref | PRIMARY, | PRIMARY | 951 | validation2.listvalue4_.ID_COMPANY_TRANSLATION,validation2.listvalue4_.ID_TRANSLATION,const | 1 | 100.00 | Using where |
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------------------+------+----------+-------------------------------------------------+
我如何强制使用 连接缓冲区（平面，BNL 连接） 第一个环境是生产环境，有更多的内存和 CPU。
在第一个环境中：
join_buffer_size............ 16777216
join_buffer_space_limit..... 2097152
第二个环境：
join_buffer_size............ 262144
join_buffer_space_limit..... 2097152
join_buffer_size和join_buffer_space_limit之间有没有link/ratio？
我们在 join_buffer_size 上配置 16Mo，因为它是一个 mysqlTuner 提示。
我将 join_buffer_space_limit 设置为 128Mo，它解决了性能问题。
所以 mysqlTuner 没有给出这个配置键的提示。
SET GLOBAL join_buffer_space_limit = 1024 * 1024 * 128;
提高性能需要时间（小时）。
https://mariadb.com/kb/en/library/multi-range-read-optimization/
我 运行 在具有巨大性能差异的 2 个环境中进行相同的查询：0.015 秒与 25 秒。
解释计划：
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------+------+----------+---------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------+------+----------+---------------------------------+
| 1 | SIMPLE | company1_ | const | PRIMARY | PRIMARY | 152 | const | 1 | 100.00 | Using temporary; Using filesort |
| 1 | SIMPLE | user2_ | ref | PRIMARY | PRIMARY | 152 | const | 1032 | 100.00 | Using where |
| 1 | SIMPLE | vacationpr5_ | eq_ref | PRIMARY | PRIMARY | 304 | user2_.ID_COMPANY_VACATION_PROFILE,.user2_.ID_VACATION_PROFILE | 1 | 100.00 | Using index |
| 1 | SIMPLE | vacationac0_ | ref | PRIMARY,I_VACATION_ACCUMULATION_EA | PRIMARY | 304 | const,.user2_.ID_USER | 4 | 100.00 | Using where |
| 1 | SIMPLE | vacationty3_ | eq_ref | PRIMARY | PRIMARY | 304 | const,.vacationac0_.ID_VACATION_TYPE | 1 | 100.00 | Using where |
| 1 | SIMPLE | vacationst6_ | eq_ref | PRIMARY | PRIMARY | 608 | user2_.ID_COMPANY_VACATION_PROFILE,.user2_.ID_VACATION_PROFILE,const,.vacationac0_.ID_VACATION_TYPE | 1 | 100.00 | Using where |
| 1 | SIMPLE | translatio9_ | eq_ref | PRIMARY | PRIMARY | 919 | vacationty3_.ID_COMPANY_TRANSLATION,.vacationty3_.ID_TRANSLATION | 1 | 100.00 | Using index |
| 1 | SIMPLE | descriptio10_ | eq_ref | PRIMARY, | PRIMARY | 951 | vacationty3_.ID_COMPANY_TRANSLATION,.vacationty3_.ID_TRANSLATION,const | 1 | 100.00 | Using where |
| 1 | SIMPLE | listvalue4_ | ALL | NULL | NULL | NULL | NULL | 5284 | 100.00 | Using where |
| 1 | SIMPLE | translatio7_ | eq_ref | PRIMARY | PRIMARY | 919 | listvalue4_.ID_COMPANY_TRANSLATION,.listvalue4_.ID_TRANSLATION | 1 | 100.00 | Using index |
| 1 | SIMPLE | descriptio8_ | eq_ref | PRIMARY | PRIMARY | 951 | listvalue4_.ID_COMPANY_TRANSLATION,.listvalue4_.ID_TRANSLATION,const | 1 | 100.00 | Using where |
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------+------+----------+---------------------------------+
接下来的讲解计划：
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------------------+------+----------+-------------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------------------+------+----------+-------------------------------------------------+
| 1 | SIMPLE | company1_ | const | PRIMARY | PRIMARY | 152 | const | 1 | 100.00 | Using temporary; Using filesort |
| 1 | SIMPLE | user2_ | ref | PRIMARY, | PRIMARY | 152 | const | 1050 | 100.00 | Using where |
| 1 | SIMPLE | vacationpr5_ | eq_ref | PRIMARY | PRIMARY | 304 | validation2.user2_.ID_COMPANY_VACATION_PROFILE,validation2.user2_.ID_VACATION_PROFILE | 1 | 100.00 | Using index |
| 1 | SIMPLE | vacationac0_ | ref | PRIMARY,I_VACATION_ACCUMULATION_EA | PRIMARY | 304 | const,validation2.user2_.ID_USER | 5 | 100.00 | Using where |
| 1 | SIMPLE | vacationty3_ | eq_ref | PRIMARY | PRIMARY | 304 | const,validation2.vacationac0_.ID_VACATION_TYPE | 1 | 100.00 | Using where |
| 1 | SIMPLE | vacationst6_ | eq_ref | PRIMARY | PRIMARY | 608 | validation2.user2_.ID_COMPANY_VACATION_PROFILE,validation2.user2_.ID_VACATION_PROFILE,const,validation2.vacationac0_.ID_VACATION_TYPE | 1 | 100.00 | Using where |
| 1 | SIMPLE | translatio9_ | eq_ref | PRIMARY | PRIMARY | 919 | validation2.vacationty3_.ID_COMPANY_TRANSLATION,validation2.vacationty3_.ID_TRANSLATION | 1 | 100.00 | Using index |
| 1 | SIMPLE | descriptio10_ | eq_ref | PRIMARY, | PRIMARY | 951 | validation2.vacationty3_.ID_COMPANY_TRANSLATION,validation2.vacationty3_.ID_TRANSLATION,const | 1 | 100.00 | Using where |
| 1 | SIMPLE | listvalue4_ | ALL | NULL | NULL | NULL | NULL | 5282 | 100.00 | Using where; Using join buffer (flat, BNL join) |
| 1 | SIMPLE | translatio7_ | eq_ref | PRIMARY | PRIMARY | 919 | validation2.listvalue4_.ID_COMPANY_TRANSLATION,validation2.listvalue4_.ID_TRANSLATION | 1 | 100.00 | Using index |
| 1 | SIMPLE | descriptio8_ | eq_ref | PRIMARY, | PRIMARY | 951 | validation2.listvalue4_.ID_COMPANY_TRANSLATION,validation2.listvalue4_.ID_TRANSLATION,const | 1 | 100.00 | Using where |
+------+-------------+---------------+--------+------------------------------------+---------+---------+---------------------------------------------------------------------------------------------------------------------------------------+------+----------+-------------------------------------------------+
我如何强制使用 连接缓冲区（平面，BNL 连接） 第一个环境是生产环境，有更多的内存和 CPU。
在第一个环境中：
join_buffer_size............ 16777216
join_buffer_space_limit..... 2097152
第二个环境：
join_buffer_size............ 262144
join_buffer_space_limit..... 2097152
join_buffer_size和join_buffer_space_limit之间有没有link/ratio？ 我们在 join_buffer_size 上配置 16Mo，因为它是一个 mysqlTuner 提示。
我将 join_buffer_space_limit 设置为 128Mo，它解决了性能问题。 所以 mysqlTuner 没有给出这个配置键的提示。
SET GLOBAL join_buffer_space_limit = 1024 * 1024 * 128;
提高性能需要时间（小时）。
https://mariadb.com/kb/en/library/multi-range-read-optimization/