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the statement throws an exception; ROLLBACK to Identifier: Roll the transaction back to the Mark Point; Set TRANSACTION: Used to set the isolation level of a transaction. The InnoDB storage engine provides transaction isolation levels of READ UNCOMMITTED, read COMMITTED, Repeatable read, and serializable.There are two main methods of MYSQL transaction processing:1, with BEGIN, ROLLBACK, commit to achieve Begin a transaction ROLLBACK transaction Rollback Commit TRANSACTION Acknowledgement 2, dir

Original: SQL Server needs to monitor which countersGeneral countersCollects server performance information for operating system servers, including processor, disk, network, memoryProcessor Processor1.1% Processor time refers to the percentage that the processor uses to perform non-idle threads. This counter allows you to determine the current percentage of CPU usage for the server.1.2% Privileged is the percentage of time that the process thread spends executing code in privileged mode. When Wi

General countersCollects server performance information for operating system servers, including processor, disk, network, memoryProcessor Processor1.1% Processor time refers to the percentage that the processor uses to perform non-idle threads. This counter allows you to determine the current percentage of CPU usage for the server. 1.2% Privileged is the percentage of time that the process thread spends executing code in privileged mode. When Windows system Services is invoked, this service ofte

Label:General countersCollects server performance information for operating system servers, including processor, disk, network, memory Processor Processor 1.1% Processor time refers to the percentage that the processor uses to perform non-idle threads. This counter allows you to determine the current percentage of CPU usage for the server. 1.2% Privileged is the percentage of time that the process thread spends executing code in privileged mode. When Windows system Services is invoked, this serv

Mysql database learning notes common operation commands 1. create a database www.2cto.com mysql> create database user; Query OK, 1 row affected (0.00 sec) 2. use this database mysql> use user; database changed3. create a table mysql> create table person (-> id int unsigned not null auto_increment primary key,-> name varchar (30)->) on this Database; Query OK, 0 rows affected (0.00 sec) 4. view the table str

large and both are moderate, the hard Disk may be a bottleneck. Before recording this counter, run diskperf-yD in the command line window of Windows 2000. If the value exceeds 80%, the memory may leak. Availiable bytes (memory): number of physical memories used. If the Available Mbytes value is small (4 MB or smaller), it indicates that the total memory on the computer may be insufficient or a program has not released the memory. Context switch/sec (

chapter for extracting data dictionaries. We will continue to provide the following chapters for non-conventional mysql recovery, such as drop recovery, truncate recovery, and delete recovery.Create a get_dict test table mysql> use xifenfei;Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> show tables;+--------------------+| Tables_in_xifenfei |+--------------------+| t_delete |+------

Mysql database learning notes-common operation commands bitsCN.com Mysql database learning notes-common Operation Commands 1. create a database Mysql> create database user; Query OK, 1 row affected (0.00 sec) 2. use this database Mysql> use user; Database changed 3. create a table in this database Mysql> create table person ( -> Id int unsigned not null auto_increment primary key, -> Name varchar (30) -> ); Query OK, 0 rows affected (0.00

', 'Customer _ id'), KEY 'idx _ fk_inventory_id '('inventory _ id '), KEY 'idx _ fk_mermer_id '('customer _ id'), KEY 'idx _ fk_staff_id' ('staff _ id '), CONSTRAINT 'fk _ polical_customer 'foreign key ('customer _ id') REFERENCES 'customer' ('customer _ id') on update cascade, CONSTRAINT 'fk _ financial_inventory 'foreign key ('inventory _ id') REFERENCES 'inventory' ('inventory _ id') on update cascade, CONSTRAINT 'fk _ comment al_staff 'foreign key ('staff _ id') REFERENCES 'staff' ('staff _

counters are as follows: Sqlperfdata Receiving counter Information Displaytoid: Counter automatically generated, record counter start informationCounterdetails: Counter is generated automatically, record the basic information of counterCounterdata: Record counter incoming data?? Sqlperfdatastat Statistics Counter Information Basic Information module:Counterdetails_collect: Used to synchronize counterdetails table data for rotation statisticsCounterdetails_collect_bak

1. Database management1.1 CREATE DatabaseCreate Database Firstdb;1.2 Show view all databasesmysql> show databases;+--------------------+| Database |+--------------------+| Information_schema || Firstdb || MySQL || Performance_schema |+--------------------+4 rows in Set (0.00 sec)1.3 Alter modifies the databaseThe ALTER command modifies the database encoding:The default database created by default does not support Chinese characters, and if we need it

, and then the two should be different. The suggestion is not casually set, we set up here just do a simple phantom reading demo, MySQL subsequent version may discard this parameter. Session 1 first adds a myid>95 record to the current readMysql> Show CREATE TABLE Test_gap_lock\g1. Row ***************************Table:test_gap_lockCreate table:create Table ' Test_gap_lock ' (' id ' int (one) not NULL,' Name ' varchar (+) DEFAULT NULL,' myID ' int (one) DEFAULT NULL,PRIMARY KEY (' id '),UNIQUE KE

database, then another transaction also accesses the data, and then used this data. Session 1:mysql> SELECT @ @global. tx_isolation; +-----------------------+ | @ @global. tx_isolation | +-----------------------+ | Repeatable-read | +-----------------------+ 1 row in Set (0.00 sec) mysql> SELECT @ @session. tx_isolation; +-----------------------+ | @ @session. tx_isolation | +-----------------------+ | Repeatable-read | +-----------------------+ 1 r

modification has not been committed to the database, then another transaction also accesses the data, and then used this data. Session 1:mysql> SELECT @ @global. tx_isolation; +-----------------------+ | @ @global. tx_isolation | +-----------------------+ | Repeatable-read | +-----------------------+ 1 row in Set (0.00 sec) mysql> SELECT @ @session. tx_isolation; +-----------------------+ | @ @session. tx_isolation | +-----------------------+ | Repe

accessing the data, and the data is modified, and this modification has not been committed to the database, then another transaction also accesses the data, and then used this data. Session 1:mysql> SELECT @ @global. tx_isolation; +-----------------------+ | @ @global. tx_isolation | +-----------------------+ | Repeatable-read | +-----------------------+ 1 row in Set (0.00 sec) mysql> SELECT @ @session. tx_isolation; +-----------------------+ | @ @s

Mysql InnoDB Line Lock Implementation methodinnodb row locks are implemented by locking the index entries on the index, which is different from Oracle, which is achieved by locking the corresponding data rows in the data block. InnoDB This type of row lock implementation is characterized by the fact that InnoDB uses row-level locks only if the data is retrieved by index criteria, otherwise INNODB will use a table lock! In practice, pay special attention to this feature of the InnoDB row lock, o

mysql; The result shows that the database is running correctly if it is changed. Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changedBasic operations on database tables view tables in the database After entering the database, check the table or the show command: mysql> show tables; +---------------------------+| Tables_in_mysql |+---------------------------+| columns_priv|| db|| event || func|| general_l

, caching, database, external interface access, in order to avoid the business execution delay blocking IO thread execution resulting in throughput degradation, usually separates the IO processing thread and the business processing thread, So our test cases also configured the business execution thread pool to examine the scheduling performance of their thread pools. mina thread pool settings IO processor: nbsp ; ioacceptor acceptor =newniosocketacceptor (Integer.parseint (Iopool));