database-deadlocks | 易学教程

Query is locking tables, can't kill that process

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问题 I have a query locking tables in MySQL (using InnoDB): UPDATE table SET status = 2 WHERE status = 3 This query caused a deadlock on the table and can't bypass it. I tried to do: show processlist then kill the process id but i can't seems to kill it I tried: kill 9588 9588 is the process id. Then I do show processlist I still see the same query on the list. How can I force killing this process and then why would this query cause a dead lock? how can I fix it? 回答1: When you run a MySQL instance

Postgres 9.3: Sharelock issue with simple INSERT

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问题 Update: Potential solution below I have a large corpus of configuration files consisting of key/value pairs that I'm trying to push into a database. A lot of the keys and values are repeated across configuration files so I'm storing the data using 3 tables. One for all unique key values, one for all unique pair values, and one listing all the key/value pairs for each file. Problem: I'm using multiple concurrent processes (and therefore connections) to add the raw data into the database.

Best Isolation Level to avoid deadlocks using an UPDATE sentence in Sql Server 2005

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问题 i need execute un update statement over an sql server table, this table is used by another process at the same time. because that sometimes deadlocks ocurs. wich Isolation Level do you recomend to avoid or minimize this deadlocks? 回答1: READ UNCOMMITTED But that allows the process to read the data before a transaction has committed, what is known as a dirty read. Further Reading You may prefer to turn on row versioning, the update creates a new version of the row and any other select

SQL deadlock on multithreaded massive delete query and bulk insert batches

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I have a batch in .NET that reads a lot of files and stores their content into a single MySQL InnoDB table with the following structure: `id` int(11) NOT NULL AUTO_INCREMENT, `Source` varchar(2) NOT NULL, `Period` char(1) NOT NULL, `idItem` int(11) NOT NULL, `StartDate` datetime NOT NULL, `MoreData` varchar(255) PRIMARY KEY (`id`), UNIQUE KEY `Combination` (`Source`,`Period`,`idItem`,`StartDate`), Where idItem is a foreign key Source, Period, and idItem are indices Combination is a unique index. To perform the table update, I then have a transaction with two steps: Delete all old rows that

Deadlock puzzle : Victim doesn't own any resource, used to kill to resolve deadlock

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I've strange deadlock graph where the victim chosen by MSSQL server 2008 isn't part of the deadlock loop. This deadlock is between select and insert . The deadlock resource is a single table where all select s want waitresource = "KEY: 6:72057594098810880 (ffffffffffff)" Question1 : Does ffffffffffff here mean they want a full range lock on whole table? Or whole key range? Or something else? We are following a rule where table will never have a row with primary key id = 0. There are few places where we do this kind of check select foo from bar where @someId = 0 OR SomeId = @someId . I also

Postgres deadlocks on concurrent upserts

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问题 We have an application which reads from a data stream and upserts that information into a database. The data is changes which occur on Google Drive which means that many events which impact the same objects can occur very close to each other. We're running into deadlocks when upserting this information into the database, here is what comes out in the log. I have reconstructed and sanitised the query for readability: ERROR: deadlock detected DETAIL: Process 10586 waits for ShareLock on

SQL Deadlock question

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问题 Is it possible in relational databases for these two statements to deadlock? I'm trying to simplify my question and example -- please just assume that these selects, which I think would normally only require sharable read-locking, now require exclusive read locks: Concurrent Connection 1: SELECT {...} FROM A JOIN B ON {...} Concurrent Connection 2: SELECT {...} FROM B JOIN A ON {...} That is, does the ordering of the joins matter? Are single statements in SQL atomic? Is A locked first and

What are locking, deadlocking issues in financial operations?

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问题 Subquestioning SQL - when should you use “with (nolock)” In one local financial institution I was rebuked by their programmers for expressing them my opinion that (their programmers' obsession with) (b)locking issues in their MS SQL Server 2005 database(s) did not make much sense to me. What are the possible issues with possible locking, blocking, deadlocking if financial operations are never updated, deleted and even incorrect operations (part of "transactions"?) are corrected by inserting

Query is locking tables, can't kill that process

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I have a query locking tables in MySQL (using InnoDB): UPDATE table SET status = 2 WHERE status = 3 This query caused a deadlock on the table and can't bypass it. I tried to do: show processlist then kill the process id but i can't seems to kill it I tried: kill 9588 9588 is the process id. Then I do show processlist I still see the same query on the list. How can I force killing this process and then why would this query cause a dead lock? how can I fix it? When you run a MySQL instance on RDS and want to kill a thread or a query for some reason, you’ll find you cannot use KILL or mysqladmin

Postgres 9.3: Sharelock issue with simple INSERT

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Update: Potential solution below I have a large corpus of configuration files consisting of key/value pairs that I'm trying to push into a database. A lot of the keys and values are repeated across configuration files so I'm storing the data using 3 tables. One for all unique key values, one for all unique pair values, and one listing all the key/value pairs for each file. Problem: I'm using multiple concurrent processes (and therefore connections) to add the raw data into the database. Unfortunately I get a lot of detected deadlocks when trying to add values to the key and value tables. I