truncate将不得不使查询缓存中的所有依赖查询失效,这可能是锁定的原因。如果查询缓存足够大,则删除缓存可能需要更长时间。 MySQL在5.5.23版本之前的处理方式即同步模式: 当要drop table的时候,会在整个操作过程中持有buffer pool的mutex,然后扫描两次LRU链表,把属于这个table的page失效掉,buffer pool
On a system with a largeInnoDBbuffer pool andinnodb_adaptive_hash_indexenabled,TRUNCATE TABLEoperations may cause a temporary drop in system performance due to an LRU scan that occurs when removing anInnoDBtable's adaptive hash index entries. The problem was addressed forDROP TABLEin MySQL 5.5.23...
Truncating anInnoDBtable that resides in a file-per-table tablespace drops the existing tablespace and creates a new one. If the tablespace was created with an earlier version and resides in an unknown directory,InnoDBcreates the new tablespace in the default location and writes the following warn...
sql delete command: a) DELETE works much slower than TRUNCATE b) DELETE generates a small amount of redo and a large amount of undo c) Transaction log - for each deleted record (deletes rows one at a time and records an entry in the transaction log for each deleted row) - slower exec...
0000000000ce40d8 mysql_execute_command(THD*, bool) 0000000000ce6fdd mysql_parse(THD*, Parser_state*) 0000000000ce7a3a dispatch_command(THD*, COM_DATA const*, enum_server_command) 0000000000ce92cf do_command(THD*) 0000000000d92a60 threadpool_process_request(THD*) ...
comparison of truncate vs delete in mysql/sqlserver DELETE DELETE is a DML Command. DELETE statement is executed using a row lock, each row in the table is locked for deletion. We can specify filters in where clause It deletes specified data if where condition exists....
Bug #50016RFE: --truncate-table in mysqldump Submitted:31 Dec 2009 20:54Modified:9 Dec 2010 19:01 Reporter:Kevin BentonEmail Updates: Status:VerifiedImpact on me: None Category:MySQL Server: mysqldump Command-line ClientSeverity:S4 (Feature request) ...
mysql_execute_command mysqld.exe!mysql_parse mysqld.exe!dispatch_command mysqld.exe!do_command mysqld.exe!handle_one_connection mysqld.exe!pthread_start mysqld.exe!_callthreadstart it's enough to run the following in a few threads: set autocommit=off; lock table t1 write ; unlock tables;...
MySQL truncate()函数的使用说明 2019-12-15 20:50 − 1、TRUNCATE()函数介绍 TRUNCATE(X,D) 是MySQL自带的一个系统函数。 其中,X是数值,D是保留小数的位数。 其作用就是按照小数位数,进行数值截取(此处的截取是按保留位数直接进行截取,没有四舍五入)。 2、数值保留规则 规则如下: 1)当 D 大于0,是对...
> to the following command: > CREATE TABLE sessions; The CREATE TABLE sessions; cmd. Returns Error 1113 (42000): A table must have at least 1 column. The show columns from sessions; cmd Returns 6 columns. > > Do I need to run the Optimize Table statement to ...