mysql innodb

It was originally used for installation. Therefore, when setting database usage (for example, 1), follow the official discuz suggestions, all selected are Non-Transactional Database Only (Only Non-transaction databases of MyISAM data engine are

Detailed analysis of InnoDB indexes in MySQL Abstract: This article introduces the InnoDB Index-related knowledge of MySQL, from various trees to the indexing principle to the details of storage. InnoDB is the default storage engine of MySQL (MyISAM

Java Application Performance optimization is a commonplace topic, the author based on personal experience, the Java performance optimization is divided into 4 levels: Application layer, database layer, framework layer, JVM layer. Through the

Later in doing WordPress, the original did not know that WordPress used the InnoDB data engine, so in the original database built a database, the beginning did not find the problem, installation, import SQL, no problem, then did not think much.

Pessimistic lock Introduction (encyclopedia): A pessimistic lock, as its name implies, is conservative in that the data is modified by the outside world (including other transactions of the system, as well as transactions from the external system),

MySQL Architecture:By: Connection pooling components, management services and tools components, SQL interface components, Query Analyzer components, optimizer components,Buffer components, plug-in storage engine, physical file composition.MySQL is a

Acid:atomic, consistent, Isolated, durable The store program provides an excellent mechanism for defining, encapsulating, and managing transactions. 1,mysql Transaction Support 1 The MySQL transaction support is not tied to the MySQL server itself,

I suddenly received an alarm from MySQL. I crashed from the database and restarted continuously. I opened the error log and found that a table was broken. If the innodb table is damaged, you cannot use repair table or other commands to repair myisam.

Fil_init mainly refers to the initialization file opening pointer hash table. All opened files are recorded in fil_system, And the buf_pool_init memory buffer pool Initialization is constructed for the hash table searched by name, corresponding to

Question: Why is transaction introduced? 1>.Data Integrity 2>.Data security 3>.Make full use of system resources to improve the system's concurrent processing capability 1.Transaction Features Transactions have four features: Atomiocity, Consistency,

The innodb engine is different from myisam in terms of statistics. Myisam has a built-in counter. Therefore, when using select count (*) from table, you can directly retrieve data from the counter. Innodb must scan the entire table once to obtain

Case DescriptionDuring the running of the scheduled script, it is found that when the SQL statement for backing up the table and the SQL statement for deleting some data in the table run simultaneously, mysql will detect the deadlock and print the

  Readers who have studied database theory should still remember the Performance Comparison Between CHAR and VARCHAR: CHAR is faster than VARCHAR because CHAR is of a fixed length and VARCHAR requires a length identifier, an extra operation is

InnoDB provides MySQL with a transaction security (ACID-compatible) storage engine with the capabilities of commit, rollback, and crash recovery. InnoDB locks row-level and also provides an Oracle-style non-locked read in the SELECT statement. These

When InnoDB is writing intensive, B-Tree extension also brings about data file extension. However, InnoDB data file extension requires mutex to protect data files, this will lead to fluctuations. Ding Qi's blog illustrates this problem:When InnoDB

Condition:Two servers: A and B. The table on server A needs to be migrated to server B.Innodb table: sysUser, number of records: 351781.The following tests are performed in MySQL 5.5.34.Start processing:1: Create a sysUser table on server B and

Recordlock: Record lock, that is, only a single row of gap lock is locked. Only one interval is locked. (note that the interval here is an open interval, that is, the boundary value is not included. Next-keylock: recordlock + gaplock, so

B + Tree Index One feature of B + tree indexes in dB is high fan-out. Generally, the height of B + tree in dB is about 2-3 layers, which means that only 2-3 Io operations are required. The current disk has approximately 100 I/O operations per

(1) udev Basics Udev can manage files stored in the/dev directory. Files are generated only after the device is connected, and are automatically deleted after the device is pulled out. It also allows you to add rules to modify the default name and

We know that there are four transaction isolation levels in the relational database standard: Uncommitted read (read uncommitted): Dirty read is allowed, that is, data that may be read from other sessions that have not committed transaction