Tag：deadlock
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Time：2021-7-21
Deadlock is no stranger to DBAs or database developers. It causes a variety of problems. Generally speaking, the developers of database applications will have certain considerations when designing, so as to avoid deadlock as much as possible, Some hard to catch deadlocks may appear, which may affect the business. Here we introduce the key search […]
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Time：2021-3-20
Every time we explain locking & blocking in SQL server, we will encounter the problem: why do we need to update locks in SQL Server? Before we explain the reasons for the specific needs, first of all, I would like to introduce to you how the update (U) lock itself responds to its compatibility when […]
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Time：2020-11-11
After some processes in Oracle are killed, the status is set to “killed”. However, the locked resources are not released for a long time. Sometimes there is no way to do so, so you have to restart the database. Now we provide a way to solve this problem, which is to kill those that cannot […]
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Time：2019-9-22
Neither session 1 nor session 2 can continue until the other party releases resources. So, SQL Server chooses a session in a deadlock as a “deadlock victim”. Note: The session of the deadlock victim is killed and the transaction is rolled back. Be careful:deadlockAnd normalblockThey are two often confused concepts. Some reasons for deadlock: 1. […]
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Time：2019-9-12
Deadlocks: refers to the phenomenon that two or more processes (threads) are waiting for each other because of competing for resources in the execution process. Without external force, they will not be able to advance. At this time, it is said that the system is in a deadlock state or that the system has a […]
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Time：2019-9-2
Through many difficult single-step debugging late at night, an ideal breakpoint has been found, and most of the lock acquisition process can be seen.The code is inlock0lock.cOfstatic enum db_err lock_rec_lock() In the function, this function shows the process of acquiring the lock and whether the lock was successful or not. Scenario 1: Delete by primary […]
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Time：2019-9-1
In the beginner’s understanding of MySQL deadlock from source code, the process of using debugging MySQL source code to view deadlock is introduced. This article describes a common case.This time we’re going to talk about love and hatred between S lock and X lock, the only index. Let’s look at a simplified example. # Constructing […]
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Time：2019-8-31
Previous articles have introduced the use of source code to debug lock-related information. Here we also use this tool to solve an online real deadlock case. It is also the first two cases of deadlock caused by SQL that we introduced. Because of the complexity of the online table structure, some simplifications are made as […]
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Time：2019-8-21
A Simple Method of Investigation and Solution Deadlock Error Reporting: ORA-00060: deadlock detection while waiting for resources Corresponding Chinese error is: ORA-00060: deadlock detected while waiting for resources Execute the following SQL to view the locked table: select object_name, machine, s.sid, s.serial# from v$locked_object l, dba_objects o, v$session s where l.object_id = o.object_id and l.session_id […]
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Time：2019-8-20
1 Background 1.1 Alarm Recently, I’ve been sorting out my notes and intending to migrate them all to EVERNOTE. Tidy up to the lock part, there happens to be a case recorded by myself, reorganize and share it to you. One day at noon, received an alarm message, DB deadlock abnormal, one minute deadlock 120. […]
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Time：2019-8-4
Preface The essence of deadlock is resource competition. Batch insertion can easily lead to deadlock if the order is inconsistent. Let’s analyze this situation. To facilitate demonstration, batch inserts are rewritten to multiple inserts. First, do a few small experiments. The simplified table structure is as follows. CREATE TABLE `t1` ( `id` int(11) NOT NULL […]
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Time：2019-6-27
This paper illustrates the transaction, locking, blocking and deadlock usage of learning notes by SQL Server. Share for your reference, as follows: 1. Affairs Implicit transaction /*================================================================== When created, dropped, fetch,open, revoke,grand, alter table,select,insert,delete,update,truncate table When the statement is first executed, the SQL Server session automatically opens a new transaction. If the implicit transaction mode […]
