how to lock ssn

Tags: read-only and tle sele generation process external HTTPS openNote: This article is reproduced from http://www.hollischuang.com/archives/934As described in the lock mechanism of a database, the task of concurrency control in a database management system (DBMS) is to ensure that the same data in the database is accessed simultaneously without disrupting the isolation and uniformity of the transaction and the consistency of the database.Optimistic

With the frontline synchronization only know the Synchronize keyword, then know that there is a lock, why also have a lock to achieve synchronization? Synchronized's limitations occupy the lock thread waiting for IO or other reasons to be blocked, without releasing the lock, Read and read can also conflict when other t

When InnoDB determines whether a row lock is in conflict, in addition to the most basic is/ix/s/x lock collision judgment, InnoDB also subdivides the lock into the following seed types: Record Lock (RK)Record locks, lock only one row of index records Gap

The lock mechanism is an important feature of a database that is different from the file system and an effective way to manage concurrent access. MySQL locks include table-level locks, page-level locks, and row-level locks. Table-level locks are the most granular locks in MySQL. They are easy to implement and consume less resources. They are supported by most MySQL engines. The most commonly used MYISAM and INNODB support table-level locks. The

In the database lock mechanism, the task of concurrency control in a database management system (DBMS) is to ensure that multiple transactions simultaneously access the same data in the database without disrupting the isolation and uniformity of the transaction and the consistency of the database. Optimistic concurrency control (optimistic lock) and pessimistic concurrency control (pessimistic

How to use PHP MySQL lock tables MySQL table lock lock tables feel like a closed space When MySQL discovers the lock tables command, it takes the table with the lock tag into the enclosing space until the unlock tables command or thread ends, and the closed space is closed

A recently maintained network server encountered performance problems, so it made major changes to the original program framework. Most of the changes are the thread working mode and data transmission mode. The final result is to change the lock usage mode. After some improvement, we can basically achieve GMB Network Adapter working at full speed. In After the performance was up to standard, I was wondering if I could use a more lightweight

In Java multithreading, you can use the keyword synchronized to implement a mutex between threads. After JDK1.5, a thread concurrency library java.util.concurrent is provided to manipulate multiple threads, including java.util.concurrent.atomic and Java.util.concurrent.lock. Atomic can realize the atomic operation of data or variable, and lock can achieve thread mutual exclusion, can realize read-write lock

Turn InnoDB row-level locksInnoDB Row-level locksCategory: Database 2013-03-13 16:40 1745 people read comments (0) favorite reports Nnodb lock mode and lock methodInnoDB implements the following two types of row locks.? Shared Lock (S): Allows a transaction to read one line, preventing other transactions from acquiring an exclusive

Pessimistic lock and optimistic lock in hibernate Locking)During the implementation of business logic, data access needs to be exclusive. For example, in the daily final computing process of the financial system, we want to process the data at a cut-off time point instead of the settlement process (which may be several seconds, or several hours), and the data changes again. At this point, we need to use som

Suppose a user (assuming a) issues the following statement to update a record: Sql> Update Employees set last_name= ' Hansijie ' where employee_id=100; Example above, at which point a user has issued an SQL statement that updates the record for employee_id 100. When a has not yet been submitted, another user D issues the following statement: sql> drop table employees; Because user A has not committed a transaction yet, the transaction has not ended, and other users cannot delete the table,

Note: This article is reproduced from http://www.hollischuang.com/archives/934As described in the lock mechanism of a database, the task of concurrency control in a database management system (DBMS) is to ensure that the same data in the database is accessed simultaneously without disrupting the isolation and uniformity of the transaction and the consistency of the database.Optimistic concurrency control (optimistic

The comparison between optimistic lock and pessimistic lock: Category Realize Characteristics Risk Pessimistic lock Rely on the lock mechanism of database layer Exclusive Nature The large overhead of database performance is often unsustainable, especially for

Tag: Code member jdk1.7 read illegal boolean return port OwnerRelease Fair Lock (based on jdk1.7.0_40)1. Unlock ()Unlock () implemented in Reentrantlock.java, the source code is as follows: Public void unlock () { sync.release (1);}Description :Unlock () is an unlock function, which is implemented by Aqs's release () function.Here, the meaning of "1" is the same as the "Get Lock function acquire (1)", wh