10 recommended courses on exclusive locks

Among row-level locks, table-level locks and page-level locks in MySQL, we have introduced that row-level locks are the most granular locks in MySQL. Row-level locks can greatly reduce conflicts in database operations. Row-level locks are divided into shared locks and exclusive locks. This article will introduce the concepts, usage and precautions of shared locks and exclusive locks in detail. Shared lock (Share Lock) Shared lock, also known as read lock, is a lock created by read operation. Other users can read the data concurrently, but no transaction can modify the data (acquire an exclusive lock on the data) until all shared locks have been released. If transaction T adds a shared lock to data A, other transactions can only add shared locks to A and cannot add exclusive locks. Transactions that are granted shared locks can only read data and cannot modify data. Usage SELECT ... LOCK IN SHARE MODE; add LOCK IN SHARE MODE after the query statement, MySQL will add a shared lock to each row in the query result, when no other thread uses an exclusive lock on any row in the query result set , you can successfully apply for the shared lock, otherwise it will be blocked. Other threads can also read tables using shared locks, and

1. Sharing the usage of shared locks and exclusive locks in MySQL

Introduction: Among row-level locks, table-level locks and page-level locks in MySQL, we have introduced that row-level locks are the locking granularity in MySQL The most detailed type of lock, row-level locks can greatly reduce conflicts in database operations. Row-level locks are divided into shared locks and exclusive locks. This article will introduce the concepts, usage and precautions of shared locks and exclusive locks in detail. Shared lock (Share Lock) Shared lock, also known as read lock, is a lock created by read operation. Other users can read the data concurrently, but no transaction can modify the data (acquire an exclusive lock on the data) until all shared locks have been released. If transaction T

##2. Mysql-detailed explanation of various lock distinctions and MVCC

Introduction: MySQL seems to have a lot of locks. After checking most of the information, what are table locks, row locks, page locks, shared locks, exclusive locks, intention locks, read locks, and write locks? Lock, optimistic lock. . I'm going, I really want to ask, are there any golden locks? I still have Fan Bingbing. . . Oops, why does it feel so messy? So let’s sort it out and summarize it. Later, there is an understanding and examples of mvcc under innodb, which is simple and easy to understand. Table/row/page-lock: table-level locking (table-level locking): M

3. Whether file_put_contents will queue up when encountering a file exclusive lock

Introduction: file_put_contents('test.txt',$data,FILE_APPEND|LOCK_EX); As shown in the above statement, if a large amount of data is being written to a file, it will take a long time. Subsequent file_put_contents must also write data to this file. Since the file has an exclusive lock, subsequent file_put...

4. mysql5.1 and mysql5.5 create indexes Speed ​​comparison

Introduction: In the MySQL5.1.X version, the process of creating and deleting a clustered index : 1. Create an empty table with the same structure as the original table, and then create a clustered index; 2. Copy the data of the original table to the new table. At this time, an exclusive lock will be added to the original table, and

5. Spin lock in SQLSERVER

Introduction: Spin lock in SQLSERVER There are many locks in SQLSERVER, such as what intention sharing Locks, exclusive locks, rows, and page locks all belong to LOCK. Latch is more lightweight than lock and only exists in memory. It is generally used to lock data pages to prevent multiple people from modifying a data page in memory at the same time. Introduced today The spin lock is more lightweight than the above two locks

6. The database cannot be locked with an exclusive lock

Introduction: When I implemented the example in the SQL video today, in order to avoid creating too many databases, I thought about changing the name of the already used database to the required one, but the computer was very naughty and always told me: Appears After this kind of mistake, there are two ways before me: First, I will find the solution online, and then proceed after solving it (maybe it will take longer than the time to create a new database);

7. ORACLE lock mechanism

#Introduction: There are two types of locks in the ORACLE lock mechanism: exclusive locks and shared locks. Exclusive locks: also known as X lock, when a user manipulates a piece of data, Oracle will automatically and implicitly add an exclusive lock to the record manipulated by the user. After the exclusive lock is added, other transactions cannot manipulate the data and can only view it. Other transactions cannot continue to add X locks. When this transaction ends, other transactions can

8. Oracle11g new features: online operation function enhancement

Introduction : Welcome to the Oracle Community Forum, interact and communicate with 2 million technical staff> The online processing function has been greatly enhanced in 11g, including online modification of table structure, online creation or rebuilding of indexes, establishment of invisible indexes, and table additions Non-null fields, online DDL and object dependency refinement, etc. Before 11g, DDL operations had to obtain the exclusive lock of the object. If

9. Exclusive lock for database transaction processing_MySQL

Introduction: Exclusive lock for database transaction processing

10. mysql second day lock_MySQL

Introduction: If there are no locks, the concurrency will be stronger, but data security will be problematic. Therefore, the database will lock the data. Shared locks and exclusive locks are read-write locks. Shared locks can be superimposed on shared locks but cannot be added on exclusive locks, while exclusive locks cannot be superimposed. Depending on the isolation level, etc., mysql will

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