????????mysql???????????mysql??γ??????????????????????????????????mysql???????????б??ū????????????????????н?????????????????????????????????????oracle???????????????oracle??????????м??????????????????????????session?????????????????????Ч???????Ч??????????mysql????????Щ???????????????????????mysql?Щ???滹?????oracle?????λ????????????????????????
??????????????
????1???????????
?????????????"mysql --help | grep my.cnf"??my.cnf?????λ???linux???????в??????????/etc/my.cnf??????mysql?????????????mysql????????????????????￡?
????1?????????????????? /etc/my.cnf  /etc/mysql/my.cnf  /SYSCONFDIR/my.cnf???????
????2??$MYSQL_HOME/my.cnf????????????
????????????????????
????1??????????????????????
????Mysql ??????????????????dynamic????????????static????
?????????????ζ???????mysql????????н??и????
?????????????????????????????????????y??и????????????????
?????????????У???Щ???????????????????????????????????????????????
????2???????????????
????????????MYSQL?????????????????????????????????????????????ν???????μ???????????MYSQL?????????MYSQL??????????????????????????????????????????????????????????????????????????????????????????????????Щ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
????3????????????
????Mysql????????????"show variables"???????????mysql5.1?汾????????????information_schema????μ?GLOBAL_VARIABLES????????в???????????????????"select * from information_schema.global_variables"??
????????????????
??????????
????mysql> SHOW VARIABLES LIKE 'max_join_size';
????mysql> SHOW GLOBAL VARIABLES LIKE 'max_join_size';
??????????
mysql> select * from information_schema.global_variables;
+---------------------------------------------------+------------------------------------------------------------------------------------------------------------------------+
| VARIABLE_NAME                                     | VARIABLE_VALUE                                                                                                         |
+---------------------------------------------------+------------------------------------------------------------------------------------------------------------------------+
| MAX_PREPARED_STMT_COUNT                           | 16382                                                                                                                  |
| INNODB_BUFFER_POOL_SIZE                           | 134217728                                                                                                              |
| HAVE_CRYPT                                        | YES                                                                                                                    |
| PERFORMANCE_SCHEMA_EVENTS_WAITS_HISTORY_LONG_SIZE | 10000                                                                                                                  |
| INNODB_VERSION                                    | 5.5.36                                                                                                                 |
| QUERY_PREALLOC_SIZE                               | 8192                                                                                                                   |
| DELAYED_QUEUE_SIZE                                | 1000                                                                                                                   |
| PERFORMANCE_SCHEMA_MAX_COND_INSTANCES             | 1000                                                                                                                   |
| SSL_CIPHER                                        |                                                                                                                        |
| COLLATION_SERVER                                  | utf8_general_ci                                                                                                        |
| SECURE_FILE_PRIV                                  |                                                                                                                        |
| TIMED_MUTEXES                                     | OFF                                                                                                                    |
| DELAYED_INSERT_TIMEOUT                            | 300                                                                                                                    |
| PERFORMANCE_SCHEMA_MAX_MUTEX_INSTANCES            | 1000000                                                                                                                |
| LC_TIME_NAMES                                     | en_US