10 recommended courses on shared 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. 10 recommended courses on exclusive locks

Introduction: 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 the transaction...

2. 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 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

##3. 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

4. MySQL database optimization (3) - MySQL pessimistic lock and optimistic lock ( Concurrency control)

Introduction: This article explains lock interpretation (shared lock), write lock (exclusive lock) ) 2. Lock granularity: table lock (table lock), row-level lock (row lock) 3. Optimistic lock and pessimistic lock pessimistic lock Exclusive lock, when a transaction operates on data, this part of the data is locked until the operation is completed After unlocking it, other transaction operations can operate on this part of the data. This will prevent other processes from reading or modifying the data in the table. Implementation: Generally use select ...for update to lock the selected data, such as

5. Let’s talk about PHP file locks, shared locks and exclusive locks. Note Click

Introduction: Let’s talk about PHP file locks, shared locks and exclusive locks. Notes

6. How to lock files under PHP_PHP tutorial

Introduction: How to lock files under PHP. ?php /* *lock_thisfile: Obtain an exclusive lock *@param $tmpFileStr The file name used as the shared lock file (you can give it any name) *@param $locktype The lock type, the default is false (not

7. How to lock files under PHP

##Introduction: How to lock files under PHP?php /. * *lock_thisfile: Obtain an exclusive lock *@param $tmpFileStr The file name used as the shared lock file (you can give it any name) *@param $locktype The lock type, the default is false (not

8. Locks in SQL Server

Introduction: When this option is selected, SQL Server does not add any locks when reading or modifying data. Lock. In this case, the user may read the data in the unfinished transaction (Uncommited Transaction) or rollback (Roll Back), which is the so-called dirty data. When this option is selected, SQL HOLDLOCK. Server will keep this shared lock until the entire transaction

##9.

About the mysql transaction row lock forupdate to implement the write lock function

Introduction: In e-commerce, there is often a small amount of inventory and a large number of people buying. How to ensure that the quantity of goods will not be purchased multiple times under large concurrency conditions. In fact, it is very simple. Just use transaction + for update. Solution. We all know that for update is actually a shared lock and can be read. But how can it not be read during execution. To put it simply: Assume that the current inventory is

10.

Summary of common ORACLE lock modes (general)

Introduction: OR ACL E is the most widely used database in the database field. Now let us Let’s quickly analyze what modes these powerful ORACLE locks have. ORACLE locks have the following modes: 0: none 1: n ul l empty 2: Row-S row sharing (RS): shared table lock 3: Row-X row Dedicated (RX): used for row modification 4: Share shared lock (S):

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