A mechanism for managing concurrent access to shared data or resources by granting temporarily exclusive access to the processes requesting the lock.

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1answer
87 views

Locking and checkout mechanism

Tables: Clients (20+ fields) Id int, Name varchar, [State] varchar, Address varhcar ClientCheckout ClientId CheckedOutAt Datetime null I'm using a separate table for managing the ...
3
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2answers
92 views

How to handle lock information?

Due to analyzing several deadlocks I used sp_blitzIndex to get an overview about locks. There is a high accordance between the tables (and views) affected by the deadlocks and the tables being ...
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0answers
82 views

Long running query with index seek

I was tuning this query, the execution plan looks fine for me but based on the statistics the Lock waits time is very high .What should i do to fix this problem? (@P0 bigint) SELECT mgmtemails0_.Id ...
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1answer
163 views

How do I insert tens of thousands of rows without locking?

I have a server that receives data from thousands of locations all over the world. Periodically, that server connects to my DB server and inserts records, one row at a time in rapid succession. There ...
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1answer
55 views

Using RowLock to enforce Once-And-Only-Once

I have a Web Service that can fire off a chain of events for an order. It does this when it gets a message telling it to (max of about 2 per second). The problem I have is that I have more than one ...
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0answers
78 views

How to avoid deadlocks when running queries on a remote server

I need to pull data from many different systems, all on remote, LIVE SQL Servers into one place for a one-off piece of work that will last a few weeks. This has to be run multiple times during the ...
2
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0answers
114 views

SELECT blocking SELECT?

I have huge outputs from pg_stat_activity and the result from the second "combination of blocked and blocking activity" report from https://wiki.postgresql.org/wiki/Lock_Monitoring (2nd version), with ...
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2answers
199 views

FLUSH TABLES WITH READ LOCK not working?

I use this command to "lock" my database, flush logs , take a LVM snapshot and release it. Testing the recover + binlogs , appear it's not working. (I discovery this when during the recover, applying ...
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1answer
138 views

Blocked sessions waiting with PAGELATCH_* wait types?

Edited : Why are sessions reporting being blocked but waiting with PAGELATCH_*, and not LCK_M_ related wait types? I previously assumed that SQL server would only report blocking sessions in the ...
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0answers
48 views

Long Transaction On File Upload Locks Strategies

I need to upload files to some SFTP or FTP servers (using libcurl) and register them in database. For this I have several tables -- locations to store files - some SFTP and FTP servers CREATE TABLE ...
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1answer
47 views

Global Read Lock for Snapshot of MySQL Data

I have a database that is entirely comprised of MyISAM tables(yes, I did not create it). I need to create a slave and start replication so we could point read-only queries there. Here is my idea: ...
2
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2answers
136 views

Is there any reason not to use foreign keys in MySQL?

I've never really used foreign keys before but I am building a project where they could come in handy. I have looked at some other large software such as some forum systems and they don't use foreign ...
2
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1answer
206 views

what happens when I try to insert data into mysql while table is locked?

Simple question but somehow impossible to find a clear answer: What happens when I try to insert data into mysql while the table is locked? 1) INSERT query fails 2) INSERT query waits until lock is ...
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2answers
131 views

How to manage concurrencies without locking tables in MySQL?

In our php app, we have a table that records orders recieved at the reception. Since we can have up to 7 agents/active accounts, how is it possible to manage the concurrencies in the orders table ...
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2answers
116 views

Oracle UPDATE statements lock race condition

Say I have a table MY_TABLE without optimistic lock column. I have the following update statement that will be executed with org.hibernate.SQLQuery: UPDATE MY_TABLE SET NAME = ? WHERE SOME_NUMBER = ? ...
5
votes
1answer
655 views

Why does UPDLOCK cause SELECTs to hang (lock)?

I've got a select in SQL SERVER that locks the whole table. Here's the setup script (make sure you don't overwrite anything) USE [master] GO IF EXISTS(SELECT 1 FROM sys.databases d WHERE d.name = ...
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2answers
449 views

Using sp_getapplock to implement a queue. Is it correct? Is there a better way?

I've been reading a series of posts by Paul White about SQL Server Isolation Levels and came across a phrase: To emphasise the point, pseudo-constraints written in T-SQL have to perform ...
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2answers
78 views

Can I make postgres more verbosely tell me what it's doing?

I'm trying to use ALTER TABLE on a live db (not in production, just poking around at a dev box and trying to learn some things) Here is the command I'm trying: psql -h $IP -p 5432 -U $DBUSER -d ...
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1answer
70 views

Deleting large amounts of cascading records with minimal locking

I'm looking for a strategy to purge large amounts of logically deleted data from a MySQL database. The deleted records are in a relatively small table, but are referred to with many ON DELETE CASACDE ...
3
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1answer
155 views

Can a Table Lock eliminate a deadlock or make it worse Oracle

We have a situation in which an Oracle Database is having deadlocks issues. I said that perhaps we should lock into some table locks, and a guys response to me was "Unless I am misunderstanding ...
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2answers
249 views

FLUSH TABLE : can't execute the given command because you have active locked tables mysql

If I execute these queries one by one, all fail except the first: Query1 : flush table tablename1 with read lock; Works Query2 : flush table tablename2 with read lock; Error : can't ...
5
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1answer
266 views

Exactly what error is returned by PostgreSQL `FOR UPDATE NOWAIT` when a selected row cannot be locked immediately?

The PostgreSQL 9.4 documentation states that adding the NOWAIT option to a SELECT FOR UPDATE means an error is generated when a row cannot be locked: To prevent the operation from waiting for ...
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2answers
82 views

Spotlight for SQL Server LockType explanation required

I have just started using Spotlight as I'm a software developer, but I am forced to identify database issues causing blocking (Spotlight shows me AWAITING_COMMAND at the points and all other processes ...
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0answers
63 views

MYSQL- concurrency issue

I use JDBC to connect to MySQL. order_items table order_item_id order_id quantity unit_price shipping_price business_id workflow_id delivery_id item_id Orders table billing_address_id ...
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0answers
52 views

PostgreSQL 9.3: Minimize locking when updating a large table with primary key

I am building a DB solution to handle a fast stream of online events. Each event UPSERTs a row in a location_update table, using its car_id primary key. Since there are very few new car_ids, the ...
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0answers
41 views

Row locks on selects

select t.*, row_number() over ( partition by t.Entity_Identifier order by t.Message_Sequence ) as seqnum from Process_Activity t (ROWLOCK) where t.Process_Id = Is it possible for ...
3
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0answers
536 views

Which is the right way to fix “Error: 1205 Lock wait timeout exceeded; try restarting transaction”

I have a PHP script that sync a local DB against external datasource. Each time the script runs I perform some triggers on the DB where INSERT or UPDATE happen. These are the the triggers for that ...
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0answers
86 views

Is it a good idea to have too many named locks?

I am using MySQL as a data store and a Java App on the top. There are many state changes that happen, and I am seeing some concurrency bugs in there. I wanted to know if I can use named locks ...
6
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1answer
238 views

Locking in Postgres for UPDATE / INSERT combination

I have two tables. One is a log table; another contains, essentially, coupon codes that can only be used once. The user needs to be able to redeem a coupon, which will insert a row into the log table ...
0
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1answer
77 views

MySql Lock Tables Blocking Logic

The MySQL documentation (5.5) for Lock tables states: Let's say that I'm trying to lock table1 and table2 in a single query, but table2 is already locked. Will MySQL hold onto a lock on table1 and ...
2
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2answers
227 views

Locking issues under transaction on Postgres

I recently got a "Out of shared memory - You might need to increase max_locks_per_transaction" error. This is a long running process where I import a bunch of CSV files after proper processing. I ...
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1answer
337 views

Why are SELECT queries in sleeping status holding open transactions

Using sp_WhoIsActive, I see that I have a lot of processes in a "sleeping" status, several for hours. I am not sure of the cause and am still troubleshooting (timeout? bad code with uncommitted ...
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221 views

MySQL queries waiting for table lock

Today I had some weird behaviour on my MySQL server that I couldn't explain. Hopefully someone can give me some debugging hints. The initial problem was that some parts of our webshop didn't seem to ...
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1answer
116 views

INSERT [TableName] SELECT * FROM [TableName]

I just ran across a query: INSERT [TableName] SELECT * FROM [TableName] Note that it is the same table. This query causes serious blocking on one of my test databases (I wanted to drop it but ...
2
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0answers
129 views

innodb update with limit locks all matching (ignores limit)

For a query similar to this: UPDATE myinnotable1 SET value=5,updated=now(),status=1 WHERE status>10 AND message="match msg" LIMIT 1; I found that innodb engine locks ALL rows matching criteria ...
2
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0answers
53 views

Why does SQL Server 2005 only use an IS lock in this scenario?

I am attempting to examine the locking behind different queries but with the same output to avoid deadlocking situations. I have the following code: SELECT MIN(ID), TextData FROM PKKEYTESTER ...
5
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2answers
172 views

Blocked Process Report -two updates causing a long block

I have a .NET application which is getting SQL update timeouts and I believe that some sort of blocking/locking is taking place which is causing this. I have ran a blocking process report on the ...
1
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1answer
63 views

Viewing Type Of Lock Being Used T-SQL - Update Lock Query Issue

I am looking for a way to determine whether SQL will take a shared lock or an update lock. Take these three queries. I believe in that in theory: Query one will take a shared lock on the pk, due ...
3
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1answer
138 views

Create Database and LCK_M_S

We are experiencing issues when creating a database in the SSMS GUI in that sometimes it times out complaining that it could not get an exclusive lock on the Model database. Other times the database ...
2
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1answer
204 views

sp_GetAppLock slow performance unusual behaviour

We had a critical issue yesterday where by a 1 second stored procedure started to take minutes to execute. I don't know the business logic as of yet, however want to understand the impact of using ...
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0answers
46 views

Does MySQL InnoDB locks multiple rows with READ_COMMITTED isolation level?

I am in trouble while resolving LOCK WAIT TIMEOUT EXCEED error with MySQL InnoDB. I have gone through this article and it says if we use isolation level READ_COMMITTED then my update query should ...
18
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5answers
1k views

In Sql Server, is there a way to check if a selected group of rows are locked or not?

We are attempting to update/delete a large number of records in a multi-billion row table. Since this is a popular table, there is a lot of activity in different sections of this table. Any large ...
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0answers
51 views

Trigger copies history table: Will removing index lock options speed up the process?

I have a trigger applied to a table to write inserts and updates to a history table. That history table can grow pretty fast, and we want to see, if we can speed up insert operation a bit. The values ...
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0answers
35 views

Transaction block on coordinator

I tried to commad a procedure described here: http://files.postgres-xl.org/documentation/add-node-datanode.html We went as far as the third step, and everything was going perfect, but during the ...
0
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1answer
184 views

How to handle lock timeout error in MySQL?

I am getting below listed error many times in my application log. 2015-05-19 10:27:57,842 ERROR [Timer-3] [org.hibernate.util.JDBCExceptionReporter] Lock wait timeout exceeded; try restarting ...
0
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1answer
78 views

How to get number of locks acquired by my MySQL Query?

How to get number of locks acquired by my MySQL update query? Is it possible using MySQL Command Prompt or MySQL Workbench? Example query : update employees set store_id = 0 where store_id = 1;
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1answer
194 views

How does the table scan in an UPDATE WHERE predicated on an unindexed column work?

I was looking into a deadlock caused by two concurrent UPDATE statements: UPDATE [table] SET [column] = 0 WHERE [unindexed_column] = @id My understanding is that because the column the WHERE is ...
0
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0answers
457 views

Removing locks in Oracle without being admin

3 wild sessions each got a row exclusive lock in the same table: SELECT * FROM DBA_DML_LOCKS; How can I remove the lock without being admin? If I was admin I would list (SID, SERIAL#) of the ...
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4answers
1k views

View locks acquired during query execution (SQL Server)

Query execution plan does not show the locking details by default, is it possible to view the locks, along with the type, acquired during the execution of a query?
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1answer
143 views

Write-lock a whole table during transaction

I need to perform a delicate operation to my table in which I will solely insert, delete and select upon all of my rows and no God may interfere with the table during this operation: the table will be ...