本日碰着一个关于MySQL求助的问题，修改表布局时碰着“ERROR 1050 (42S01): table xxx already exits”

 mysql> ALTER TABLE DAY_BOOK_REPORT  ADD UNIT_PRICE_PCS   DOUBLE(12,2) DEFAULT NULL;

ERROR 1050 (42S01): TABLE 'INVGSP/#SQL-IB379' ALREADY EXISTS

mysql>

查抄了后，发明表DAY_BOOK_REPORT确实不存在字段UNIT_PRICE_PCS，可是给表加字段时就报这个错误，劳务派遣管理系统，遂咨询了一下他详细的操纵进程，反馈是其时在做大量数据更新，然后给这个表增加字段时，溘然报“DB connect fail”， 登录MySQL处事器查抄发明MySQL处事已经挂了，MySQL版本为5.6.20-enterprise-commercial-advanced-log，查抄错误日志，发明有下面错误信息：

2018-03-31 23:29:16 7f09c1830700 InnoDB: Error: Write to file ./INVOICE/#sql-ib379.ibd failed at offset 600834048.
InnoDB: 1048576 bytes should have been written, only 446464 were written.
InnoDB: Operating system error number 0.
InnoDB: Check that your OS and file system support files of this size.
InnoDB: Check also that the disk is not full or a disk quota exceeded.
InnoDB: Error number 0 means 'Success'.
InnoDB: Some operating system error numbers are described at
InnoDB: http://dev.mysql.com/doc/refman/5.6/en/operating-system-error-codes.html
15:29:16 UTC - mysqld got signal 11 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed, 
something is definitely wrong and this may fail.
 
key_buffer_size=8388608
read_buffer_size=131072
max_used_connections=120
max_threads=151
thread_count=6
connection_count=6
It is possible that mysqld could use up to 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 68245 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.
 
Thread pointer: 0x9ac95e0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 7f09c182fe10 thread_stack 0x40000
/usr/sbin/mysqld(my_print_stacktrace+0x35)[0x946155]
/usr/sbin/mysqld(handle_fatal_signal+0x3d8)[0x6a58c8]
/lib64/libpthread.so.0[0x3a6b60f710]
/usr/sbin/mysqld[0xa45a2b]
/usr/sbin/mysqld[0xa50f5a]
/usr/sbin/mysqld[0x9e1afd]
/usr/sbin/mysqld[0x9e55a5]
/usr/sbin/mysqld[0x96aec5]
/usr/sbin/mysqld[0x7790a5]
/usr/sbin/mysqld(_Z17mysql_alter_tableP3THDPcS1_P24st_ha_create_informationP10TABLE_LISTP10Alter_infojP8st_orderb+0x1e54)[0x77b204]
/usr/sbin/mysqld(_ZN19Sql_cmd_alter_table7executeEP3THD+0x4a5)[0x87fab5]
/usr/sbin/mysqld(_Z21mysql_execute_commandP3THD+0x3d4f)[0x72aa4f]
/usr/sbin/mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x318)[0x72de48]
/usr/sbin/mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x11b6)[0x72f7f6]
/usr/sbin/mysqld(_Z10do_commandP3THD+0xd7)[0x7310a7]
/usr/sbin/mysqld(_Z24do_handle_one_connectionP3THD+0x116)[0x6f8856]
/usr/sbin/mysqld(handle_one_connection+0x45)[0x6f8935]
/usr/sbin/mysqld(pfs_spawn_thread+0x126)[0xb153e6]
/lib64/libpthread.so.0[0x3a6b6079d1]
/lib64/libc.so.6(clone+0x6d)[0x3a6b2e89dd]
 
Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (7f095e93b2e0): is an invalid pointer
Connection ID (thread ID): 4237691
Status: NOT_KILLED

从错误提示看，MySQL在往./INVGSP/#sql-ib379.ibd文件写入数据时，碰着了错误，可是最终写入乐成（InnoDB: Operating system error number 0.），按错误日志内里的信息提示排盘查题：

InnoDB: Check that your OS and file system support files of this size.
InnoDB: Check also that the disk is not full or a disk quota exceeded.

最终查抄发明MySQL数据文件地址的分区已经爆了，看错误提示，很有大概是因为空间问题，导致MySQL历程Crash掉了，而MySQL在ALTER TABLE操纵进程中瓦解，那么最终大概会在InnoDB表空间中生成一个孤独的中间表（orphaned intermediate table）。 其实#sql-ib379.ibd就是在修改DAY_BOOK_REPORT时，由于MySQL历程Crash掉后生成的孤独中间表。查抄如下所示：

mysql> show variables like '%innodb_file_per_table%';
+-----------------------+-------+
| Variable_name         | Value |
+-----------------------+-------+
| innodb_file_per_table | ON    |
+-----------------------+-------+
1 row in set (0.00 sec)
 
mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_TABLES WHERE NAME LIKE '%#sql%';
+----------+--------------------+------+--------+-------+-------------+------------+---------------+
| TABLE_ID | NAME               | FLAG | N_COLS | SPACE | FILE_FORMAT | ROW_FORMAT | ZIP_PAGE_SIZE |
+----------+--------------------+------+--------+-------+-------------+------------+---------------+
|      650 | INVOICE/#sql-ib379 |    1 |     65 |   636 | Antelope    | Compact    |             0 |
+----------+--------------------+------+--------+-------+-------------+------------+---------------+
1 row in set (0.04 sec)
 
mysql>

官方文档https://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting-datadict.html关于孤独中间表的先容如下：

Orphan Intermediate Tables

If MySQL exits in the middle of an in-place ALTER TABLE operation (ALGORITHM=INPLACE), you may be left with an orphan intermediate table that takes up space on your system. This section describes how to identify and remove orphan intermediate tables.

Intermediate table names begin with an #sql-ib prefix (e.g., #sql-ib87-856498050). The accompanying .frm file has an #sql-* prefix and is named differently (e.g., #sql-36ab_2.frm).

To identify orphan intermediate tables on your system, you can view Table Monitor output or query INFORMATION_SCHEMA.INNODB_SYS_TABLES. Look for table names that begin with #sql. If the original table resides in a file-per-tabletablespace, the tablespace file (the #sql-*.ibd file) for the orphan intermediate table should be visible in the database directory. 

找到对应的frm文件(这里是#sql-71a_40a97b.frm )，然后将其定名为#sql-ib379.frm（数据文件为#sql-ib379.ibd）， 然后删除表（对应的文件会删除）即可办理上面这个问题。

# mv "#sql-71a_40a97b.frm" "#sql-ib379.frm"


mysql>  DROP TABLE `#mysql50##sql-ib379`

    -> ;

Query OK, 0 rows affected (0.11 sec)
 

mysql>  SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_TABLES WHERE NAME LIKE '%#sql%';

Empty set (0.01 sec)
 

mysql>

小我私家还测试了网上别的一种要领，劳务派遣管理系统，昆山软件开发，就是首先先删除#sql开头的这些文件，然后拷贝源表数据到备份表，接着删除原表，最后将备份表重定名为源表。添加相关索引。这种要领也能办理这个问题。

mysql> show index from DAY_BOOK_REPORT;
 
mysql> create table DAY_BOOK_REPORT_BK as select * from DAY_BOOK_REPORT;
 
mysql> drop table DAY_BOOK_REPORT;
 
mysql> rename table DAY_BOOK_REPORT_BK to DAY_BOOK_REPORT;
 
mysql>ALTER TABLE DAY_BOOK_REPORT ADD INDEX INDEX_NAME (column_list) --按照实际环境输入详细字段
 
mysql>ALTER TABLE DAY_BOOK_REPORT ADD UNIQUE (column_list) --按照实际环境输入详细字段
 
mysql>ALTER TABLE DAY_BOOK_REPORT ADD PRIMARY KEY (column_list) --按照实际环境输入详细字段

参考资料：