之前看到mysql二进制日志后面会加一个以数字递增为结尾的后缀，一直在想当尾数到达999999后会发生什么情况，先查了一下官网，对后缀有这样一句介绍：The server creates binary log files in sequence by adding a numeric suffix to the base name
就是说会在你定义的二进制文件名后再加多一个数字为结尾，那么这个数最大为多少呢(此次实验版本为5.7.12)？
我们先让其到999999，再flush logs看一下，发现还是可以继续递增
-rw-r-----. 1 mysql mysql 241 Aug 11 19:05 binlog57.1000000
-rw-r-----. 1 mysql mysql 194 Aug 11 19:05 binlog57.1000001
-rw-r-----. 1 mysql mysql 177 Aug 11 19:02 binlog57.999991
-rw-r-----. 1 mysql mysql 200 Aug 11 19:03 binlog57.999992
-rw-r-----. 1 mysql mysql 200 Aug 11 19:03 binlog57.999993
-rw-r-----. 1 mysql mysql 200 Aug 11 19:04 binlog57.999994
-rw-r-----. 1 mysql mysql 200 Aug 11 19:04 binlog57.999995
-rw-r-----. 1 mysql mysql 200 Aug 11 19:04 binlog57.999996
-rw-r-----. 1 mysql mysql 200 Aug 11 19:04 binlog57.999997
-rw-r-----. 1 mysql mysql 468 Aug 11 19:05 binlog57.999998
-rw-r-----. 1 mysql mysql 241 Aug 11 19:05 binlog57.999999
我们再把后面改成int的最大值（4294967296）再看看，发现依旧可以继续向上加：
-rw-r-----. 1 mysql mysql 241 Aug 11 19:05 binlog57.4294967290
-rw-r-----. 1 mysql mysql 244 Aug 12 09:10 binlog57.4294967291
-rw-r-----. 1 mysql mysql 244 Aug 12 09:10 binlog57.4294967292
-rw-r-----. 1 mysql mysql 244 Aug 12 09:11 binlog57.4294967293
-rw-r-----. 1 mysql mysql 244 Aug 12 09:11 binlog57.4294967294
-rw-r-----. 1 mysql mysql 244 Aug 12 09:11 binlog57.4294967295
-rw-r-----. 1 mysql mysql 244 Aug 12 09:11 binlog57.4294967296
-rw-r-----. 1 mysql mysql 244 Aug 12 09:11 binlog57.4294967297
-rw-r-----. 1 mysql mysql 244 Aug 12 09:11 binlog57.4294967298
按照mysql的数据类型，我们还有更大的bigint，我们再次将此后缀改在2^64，即（18446744073709551616）
重启之后发现此值自动变为了9223372036854775808，即2^63：
-rw-r-----. 1 mysql mysql 520 Aug 12 09:22 binlog57.9223372036854775808
再flush log都也不会变了。
那此时如果我插入记录，并flush logs，binlog里面的内容会怎样？
我们插入一条记录：
[zejin] 3301>insert into t_users values(7,'test');
Query OK, 1 row affected (0.00 sec)
解释下binlog:
解析一：
[root@zejin240 I3301]# mysqlbinlog --no-defaults -vv binlog57.9223372036854775808 /*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/; /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/; DELIMITER /*!*/; # at 4 #160812 9:26:52 server id 3301 end_log_pos 123 CRC32 0x500b46f2 Start: binlog v 4, server v 5.7.12-log created 160812 9:26:52 # Warning: this binlog is either in use or was not closed properly. BINLOG ' 3CWtVw/lDAAAdwAAAHsAAAABAAQANS43LjEyLWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAXwAEGggAAAAICAgCAAAACgoKKioAEjQA AfJGC1A= '/*!*/; # at 123 #160812 9:26:52 server id 3301 end_log_pos 194 CRC32 0x4cf85ce2 Previous-GTIDs # a97983fc-5a29-11e6-9d28-000c29d4dc3f:1802-1806 # at 194 #160812 9:28:13 server id 3301 end_log_pos 259 CRC32 0x3e10b5ae GTID last_committed=0 sequence_number=1 SET @@SESSION.GTID_NEXT= 'a97983fc-5a29-11e6-9d28-000c29d4dc3f:1807'/*!*/; # at 259 #160812 9:28:13 server id 3301 end_log_pos 332 CRC32 0xe3e2c0d3 Query thread_id=2 exec_time=0 error_code=0 SET TIMESTAMP=1470965293/*!*/; SET @@session.pseudo_thread_id=2/*!*/; SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/; SET @@session.sql_mode=1436549152/*!*/; SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/; /*!C utf8 *//*!*/; SET @@session.character_set_client=33,@@session.collation_connection=33,@@session.collation_server=33/*!*/; SET @@session.lc_time_names=0/*!*/; SET @@session.collation_database=DEFAULT/*!*/; BEGIN /*!*/; # at 332 #160812 9:28:13 server id 3301 end_log_pos 386 CRC32 0xb37366c7 Table_map: `zejin`.`t_users` mapped to number 109 # at 386 #160812 9:28:13 server id 3301 end_log_pos 431 CRC32 0xf13017e6 Write_rows: table id 109 flags: STMT_END_F BINLOG ' LSatVxPlDAAANgAAAIIBAAAAAG0AAAAAAAEABXplamluAAd0X3VzZXJzAAIDDwKWAADHZnOz LSatVx7lDAAALQAAAK8BAAAAAG0AAAAAAAEAAgAC//wHAAAABHRlc3TmFzDx '/*!*/; ### INSERT INTO `zejin`.`t_users` ### SET ### @1=7 /* INT meta=0 nullable=0 is_null=0 */ ### @2='test' /* VARSTRING(150) meta=150 nullable=0 is_null=0 */ # at 431 #160812 9:28:13 server id 3301 end_log_pos 462 CRC32 0x58679478 Xid = 20 COMMIT/*!*/; ERROR: Error in Log_event::read_log_event(): 'read error', data_len: 134217728, event_type: -27 SET @@SESSION.GTID_NEXT= 'AUTOMATIC' /* added by mysqlbinlog */ /*!*/; DELIMITER ; # End of log file /*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/; /*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
[zejin] 3301>flush logs;
Query OK, 0 rows affected (0.01 sec)
解析二：
[root@zejin240 I3301]# mysqlbinlog --no-defaults -vv binlog57.9223372036854775808 /*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/; /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/; DELIMITER /*!*/; # at 4 #160812 9:29:15 server id 3301 end_log_pos 123 CRC32 0x1a8f3783 Start: binlog v 4, server v 5.7.12-log created 160812 9:29:15 # Warning: this binlog is either in use or was not closed properly. BINLOG ' ayatVw/lDAAAdwAAAHsAAAABAAQANS43LjEyLWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAXwAEGggAAAAICAgCAAAACgoKKioAEjQA AYM3jxo= '/*!*/; # at 123 #160812 9:29:15 server id 3301 end_log_pos 194 CRC32 0xfe26d3f7 Previous-GTIDs # a97983fc-5a29-11e6-9d28-000c29d4dc3f:1802-1807 # at 194 #160812 9:28:13 server id 3301 end_log_pos 259 CRC32 0x3e10b5ae GTID last_committed=0 sequence_number=1 SET @@SESSION.GTID_NEXT= 'a97983fc-5a29-11e6-9d28-000c29d4dc3f:1807'/*!*/; # at 259 #160812 9:28:13 server id 3301 end_log_pos 332 CRC32 0xe3e2c0d3 Query thread_id=2 exec_time=0 error_code=0 SET TIMESTAMP=1470965293/*!*/; SET @@session.pseudo_thread_id=2/*!*/; SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/; SET @@session.sql_mode=1436549152/*!*/; SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/; /*!C utf8 *//*!*/; SET @@session.character_set_client=33,@@session.collation_connection=33,@@session.collation_server=33/*!*/; SET @@session.lc_time_names=0/*!*/; SET @@session.collation_database=DEFAULT/*!*/; BEGIN /*!*/; # at 332 #160812 9:28:13 server id 3301 end_log_pos 386 CRC32 0xb37366c7 Table_map: `zejin`.`t_users` mapped to number 109 # at 386 #160812 9:28:13 server id 3301 end_log_pos 431 CRC32 0xf13017e6 Write_rows: table id 109 flags: STMT_END_F BINLOG ' LSatVxPlDAAANgAAAIIBAAAAAG0AAAAAAAEABXplamluAAd0X3VzZXJzAAIDDwKWAADHZnOz LSatVx7lDAAALQAAAK8BAAAAAG0AAAAAAAEAAgAC//wHAAAABHRlc3TmFzDx '/*!*/; ### INSERT INTO `zejin`.`t_users` ### SET ### @1=7 /* INT meta=0 nullable=0 is_null=0 */ ### @2='test' /* VARSTRING(150) meta=150 nullable=0 is_null=0 */ # at 431 #160812 9:28:13 server id 3301 end_log_pos 462 CRC32 0x58679478 Xid = 20 COMMIT/*!*/; # at 462 #160812 9:29:15 server id 3301 end_log_pos 521 CRC32 0xc86262e6 Rotate to binlog57.9223372036854775808 pos: 4 SET @@SESSION.GTID_NEXT= 'AUTOMATIC' /* added by mysqlbinlog */ /*!*/; DELIMITER ; # End of log file /*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/; /*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
再插入一条记录:
[zejin] 3301>insert into t_users values(8,'test1');
Query OK, 1 row affected (0.01 sec)
解析三：
[root@zejin240 I3301]# mysqlbinlog --no-defaults -vv binlog57.9223372036854775808 /*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/; /*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/; DELIMITER /*!*/; # at 4 #160812 9:29:15 server id 3301 end_log_pos 123 CRC32 0x1a8f3783 Start: binlog v 4, server v 5.7.12-log created 160812 9:29:15 # Warning: this binlog is either in use or was not closed properly. BINLOG ' ayatVw/lDAAAdwAAAHsAAAABAAQANS43LjEyLWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAXwAEGggAAAAICAgCAAAACgoKKioAEjQA AYM3jxo= '/*!*/; # at 123 #160812 9:29:15 server id 3301 end_log_pos 194 CRC32 0xfe26d3f7 Previous-GTIDs # a97983fc-5a29-11e6-9d28-000c29d4dc3f:1802-1807 # at 194 #160812 9:31:09 server id 3301 end_log_pos 259 CRC32 0xad1dc1f6 GTID last_committed=0 sequence_number=1 SET @@SESSION.GTID_NEXT= 'a97983fc-5a29-11e6-9d28-000c29d4dc3f:1808'/*!*/; # at 259 #160812 9:31:09 server id 3301 end_log_pos 332 CRC32 0x62cde234 Query thread_id=2 exec_time=0 error_code=0 SET TIMESTAMP=1470965469/*!*/; SET @@session.pseudo_thread_id=2/*!*/; SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/; SET @@session.sql_mode=1436549152/*!*/; SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/; /*!C utf8 *//*!*/; SET @@session.character_set_client=33,@@session.collation_connection=33,@@session.collation_server=33/*!*/; SET @@session.lc_time_names=0/*!*/; SET @@session.collation_database=DEFAULT/*!*/; BEGIN /*!*/; # at 332 #160812 9:31:09 server id 3301 end_log_pos 386 CRC32 0xd3a0edfd Table_map: `zejin`.`t_users` mapped to number 109 # at 386 #160812 9:31:09 server id 3301 end_log_pos 432 CRC32 0x9146b5b0 Write_rows: table id 109 flags: STMT_END_F BINLOG ' 3SatVxPlDAAANgAAAIIBAAAAAG0AAAAAAAEABXplamluAAd0X3VzZXJzAAIDDwKWAAD97aDT 3SatVx7lDAAALgAAALABAAAAAG0AAAAAAAEAAgAC//wIAAAABXRlc3QxsLVGkQ== '/*!*/; ### INSERT INTO `zejin`.`t_users` ### SET ### @1=8 /* INT meta=0 nullable=0 is_null=0 */ ### @2='test1' /* VARSTRING(150) meta=150 nullable=0 is_null=0 */ # at 432 #160812 9:31:09 server id 3301 end_log_pos 463 CRC32 0x594574f2 Xid = 22 COMMIT/*!*/; ERROR: Error in Log_event::read_log_event(): 'read error', data_len: 150994944, event_type: -27 SET @@SESSION.GTID_NEXT= 'AUTOMATIC' /* added by mysqlbinlog */ /*!*/; DELIMITER ; # End of log file /*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/; /*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
发现flush log后解析的binlog中会产生一个错误：
ERROR: Error in Log_event::read_log_event(): 'read error', data_len: 150994944, event_type: -27
对比解析一与解释三就会发现，超过此最大值后，flush log命令会覆盖掉之前的数据，并且binlog后面的数字后缀永远停留在9223372036854775808。这种情况下肯定是有问题的。
不过话说回来，你说生产环境下什么时候些值才可能超过这个数呢，按每秒产生1个binlog的速度来计算，我们需要9223372036854775808/60/60/24/365/10^9=2924.7亿年，估计它没挂，地球都挂了，它会陪你活到天荒地老……