database-deadlocks

问题 my application is having deadlock issue where there is a possibility of conflict from three different sides: 1) MySQL database event - that executed every minutes and run couple of update commands in transactions. 2) Background task = that run every seconds and run couple of insert/update commands in transaction.(doctrine) 3) Main FrontEnd API call - based on incoming request, run insert/update commands. Because of high traffic, request density, this is also of high density.(doctrine) So,

问题 This is a follow up on my previous question (you can skip it as I explain in this post the issue): MySQL InnoDB SELECT...LIMIT 1 FOR UPDATE Vs UPDATE ... LIMIT 1 Environment: JSF 2.1 on Glassfish JPA 2.0 EclipseLink and JTA MySQL 5.5 InnoDB engine I have a table: CREATE TABLE v_ext ( v_id INT NOT NULL AUTO_INCREMENT, product_id INT NOT NULL, code VARCHAR(20), username VARCHAR(30), PRIMARY KEY (v_id) ) ENGINE=InnoDB DEFAULT CHARSET=UTF8; It is populated with 20,000 records like this one (

问题 Facing a deadlock in SQL server database and can see deadlock entry in SQL logs. How the log entries can be used to find the reason for this deadlock? 回答1: Deadlock information is captured by the system_health Extended Events trace by default. No need to turn on additional trace flags. Information from the xml_deadlock event can be viewed from SSMS Object Explorer (Management-->Extended Events-->Sessions--system_health) or with T-SQL. Below is an example query to get the deadlock xml from the

问题 I am seeing a deadlock with MySQL 5.6 because of what seems like trying to lock the same row/s twice. From the snippet below, rows where id = (11, 12, 13, 14, 15) already have a lock. And when another transaction tried to acquire a lock on these, MySQL failed the transaction detecting a deadlock. Is my reading of this correct? If so, is there anything in MySQL 5.6 to get over this? FWIW, the same code in 5.5 worked just fine (for several hundreds of iterations). ------------------------

问题 Background information I am trying to understand how postgresql well enough so that I can ensure that my web app will not fail when users are simultaneously trying to update the same record. For testing purposes, I have created two scripts - one script creates / defines the transaction block and the second script simulates load (and attempts to create conflicts) by calling script 1. Code Here's what script 1 looks like: http://pastebin.com/6BKyx1dW And here's what script two looks like: http:

问题 We work with DB2 effective version 8 (more or less, so no CUR_COMMIT) on z/OS. In our (Java based, though this should not be relevant) application a method exists which runs in a transaction and deletes multiple records from a table called, say, MY_TABLE, based on the value of a certain column which we will call SPECIAL_COLUMN, executing the statement DELETE FROM MY_TABLE WHERE SPECIAL_COLUMN=? Apart from executing this statement, some other SQL statements get executed which I omit because

问题 Lets say there are 3 users A,B,C hitting to the db and runs a update query at the same point of time(Not even a milisecond diff). Example Scenario : Lets say we have a ref_Product_qty table which stores the product id and quantiy available in the warehouse. Now we have a "Add to Cart" button on our site. When thousand of user will hit this button at the same time there is a sure possibility of overlapping and we have this query running behind. if (qty > 0) { UPDATE ref_Product_qry SET qty =

问题 I have a stored procedure in which I am updating a table multiple times, but this is causing deadlock in my case when multiple sessions run this procedure. I have tried to use Begin Trans and Commit statements but not working for me. I have read that creating index can solve my problem but how is it going to help and on which column should I create (which type of) index? UPDATE lessonPlanSkill SET PreviousProficiency = lessonPlanSkill.CurrentProficiency , PreviousAccuracy = lessonPlanSkill

问题 I am seeing some unexplained deadlocks in our Postgres database. Simplifying the related queries, one of the transactions involved in the deadlock is: BEGIN; UPDATE A SET CHUNK_ID=1, STATUS='PROCESSING' WHERE ID IN ( SELECT ID FROM A WHERE CHUNK_ID IS NULL ORDER BY O_ID LIMIT 1000 FOR UPDATE ); COMMIT; and the other one is: BEGIN; UPDATE A SET STATUS='SENT' WHERE ID = 1; UPDATE A SET STATUS='SENT' WHERE ID = 2; UPDATE A SET STATUS='SENT' WHERE ID = 3; ... COMMIT; My question is how is it

问题 I'm in the process of learning a more complex SQL Server 2008 techniques so I apologize in advance if I ask a too obvious question. I have the following table created as such: CREATE TABLE [dbo].[t_Log_2] ( [id] INT NOT NULL IDENTITY(1,1) PRIMARY KEY, [oid] INT, [idtm] DATETIME2, [odtm] DATETIME2, [type] TINYINT, [state] TINYINT, [huid] UNIQUEIDENTIFIER, [cnm] NVARCHAR(256), [cmdl] NVARCHAR(256), [batt] TINYINT, [dvtp0] SMALLINT, [dvtp1] SMALLINT ); CREATE INDEX idx_idt ON [dbo].[t_Log_2](