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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3
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44 views

ODBC Connections locking tables in SQL Server

We have an ERP system that is a little less than modern, the backend is currently sitting on a SQL Server 2008 R2 installation. We have through mandate of management (isn't that always the case) the ...
3
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0answers
74 views

MySQL queries waiting for other queries to finish

We have 30-40 different projects in Python and PHP that update, insert and select more than 1 million rows of data in MySQL DB every day. Currently we use InnoDB Engine for our tables. The problem: ...
3
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0answers
636 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 ...
3
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0answers
418 views

Slow transactions, many locks

At high load conditions the server app stops responding to client because begin/commit statements are executing very slowly (some take 15 seconds). The queries are simple - insert, update two columns ...
2
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0answers
52 views

Select Query with S lock wins on Insert with IX lock in deadlock

Select Query with S lock wins on Insert with IX lock in deadlock in Sql Server 2008R2. Attaching the deadlock xml file.Please help! http://pastebin.com/nY9EXbS8 This is from the error log by ...
2
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0answers
19 views

In PostgreSQL, can you read from an index during a ALTER INDEX … SET TABLESPACE operation?

I have a PostgreSQL 9.3 server, and there's a large index that I want to move to another tablespace on another disk, because I want to free up space on the original disk. However this is a production ...
2
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0answers
38 views

How to avoid row locks on both tables joined in an update?

I have little knowledge about MySQL internals, but I'm experiencing that in a query like: UPDATE t1 JOIN t2 ON t1.id = t2.id SET t1.a = x, t1.b = y, [, ...] WHERE [ ... ] rows from both t1 and ...
2
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0answers
26 views

Does Disabling Page Level Locking Have an Adverse Effect on Other DBs

I got the following from a vendor about what their software (“IM”) needs: “IM needs its own SQL Server Instance if the DB is installed on a shared SQL server. This is a mandatory prerequisite because ...
2
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74 views

SQL Server Check Constraint Lock Order

I'm having problems with SQL Server 2012 filetable. Filetable defines an check constraint on a path_locator field with definition as: /*ParentsAreDirectories*/ (filetable_parents_are_directories((...
2
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0answers
152 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 ...
2
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173 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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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 ...
2
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0answers
66 views

SQL Server 2008 R2 - Should I be worried at this statistics regarding indices causing locks?

We have some mild table locking issue during our peak hours so I figured the following query query taken from this site would be a good start. And boy, does it show me some seriously concerning ...
2
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0answers
969 views

How to make SSAS Commit Write take less time

We're using SQL Server Analysis Server 2012 (Enterprise) and have a process to update the cube during the day. This process is running pretty well until it gets to the final part of processing where ...
2
votes
0answers
4k views

Oracle Select Query Over Database Link Suddenly Hangs Endlessly

I have a query that's been in use for years and today it started hanging endlessly. I took the query apart and found the piece causing it to hang is a simple join on a primary key that should run like ...
2
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0answers
430 views

Oracle locked sessions with ASP.Net

I am connecting to an Oracle database in ASP.Net using SQLDataSource. My connection string is: <add name="ConnectionString3" connectionString="Data Source=sml; User ID=sml; Password=sml; Unicode=...
1
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0answers
62 views

How to make a PostgreSQL trigger thread-safe

I want to make my PostgreSQL trigger function do something like incrementing counters etc (something complex with multiple queries etc) thread-safely (so the same function triggered concurrently won't ...
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0answers
36 views

2 phase locking with added increment mode

I have this assignment question where increment mode is added in addition to read and write lock modes in two phase locking.But I cant seem to figure out whether each lock mode has its own seperate ...
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0answers
50 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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0answers
42 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 ...
1
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0answers
121 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 (...
1
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0answers
75 views

Average Waiter Count increasing

I am in a nightmare. We have deployed an application to a UAT environment, which has only 7 users. Since then, we have noticed in the logs, a lot of deadlocks, and processes being victims and things. ...
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81 views

Handling this multi-threading scenario in the database?

I am working on sample bus ticket booking application,in I am facing these two multi-threading scenarios. Scenario 1 1: Let's say there are two users, they both pick a particular seat and submit form....
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35 views

MySQL - Transactions and causality

I'm new to MySQL's LOCK and TRANSACTION and have a question about different isolation levels of a transaction: Given two transactions executing the same code (auto-commit is false): (1) get data of ...
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0answers
270 views

Postgres advisory lock deadlocks itself?

I am executing pg_advisory_locks using the following set of statements: SELECT pg_advisory_lock(317,2); UPDATE posts SET dislikers = array_remove(dislikers, 7) WHERE id = 317; update posts set ...
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156 views

Update on a small table times out

We use Microsoft SQL Server Express Edition with Advanced Services 2008 R2 SP2 We have two locations. Each location has one sql server that serves about 20 client computers. Client computers are ...
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0answers
110 views

MySQL WRITE LOCK Not Preventing Inserts

This should be a simple task. Can someone tell me why the below code is still inserting rows? lock table wp_postmeta write; insert into wp_postmeta values (null, 1,'test','test'); I've checked my ...
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0answers
208 views

MySQL replication of single DB to same server

I have a DB Server running CentOS 6.4 and MySQL 5.5 from RPMs (not source). I have dozens of databases but one of them is being hit quite hard with large selects which locks out other updates which ...
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0answers
954 views

Unable to insert into or update table

A have the following table in a SQL Server 2000 database (service pack 2), with about 600,000 rows: Id [int, primary key] Form [int] Element [int] Data [char(8000)] MoreData [varchar(8000)] ...
0
votes
0answers
12 views

Lock Request timeout causing Orphaned spids

I have an issue where an application with a single connection to the database, got a lock request timeout. In my mind a lock request timeout can only happen if a query waits for a resource for over 5 ...
0
votes
0answers
32 views

How to minimize locking / maximize update throughput on small table

I have problem on SQL Server. I have a very, very small table which has a very high update frequency. CREATE TABLE [dbo].[counters]( [id] [int] NOT NULL, [val] [bigint] NOT NULL) Table has ...
0
votes
0answers
25 views

Schema Locks blocking during Alter Table Add Constraint?

I am dealing with a customer using MS SQL Server with Entity Framework to generate their database upgrades. EF generates a "Migration Script", which in this case is a fairly straightforward collection ...
0
votes
0answers
29 views

How to troubleshoot the “lock request timeout exceeded” error?

Scenario: Usually I received "lock request time-out exceeded" message on client's server. This is not fixed by time and other things. I am getting details of executed SQLs by running query with sys....
0
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0answers
77 views

Why does CREATE TRIGGER lock a table in MySql?

What I've done? I tried to execute a CREATE TRIGGER statement on a table with about 4.x million rows. The trigger I tried to create was a INSERT trigger. And it looked like that the whole table was ...
0
votes
0answers
33 views

PostgreSQL not running every update on my script

I'm running a dozen update statements on a loop and some updates just won't happen (they return 0 affected rows), If i recall the script it will slowly update the rows, I don't know how to debug this....
0
votes
0answers
27 views

MySQL lock on READ and concurrent execution

I'm building a small application (in Java) and I have arrived to a point where, depending on a field in one my database table the action to be executed has to be completely unique. I have a ...
0
votes
0answers
87 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 ...
0
votes
0answers
98 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 ...
0
votes
0answers
71 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 ...
0
votes
0answers
64 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 ...
0
votes
0answers
253 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 ...
0
votes
0answers
51 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 ...
0
votes
0answers
545 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 ...
0
votes
0answers
295 views

Postgresql: Update or insert stuck

I'm running update-or-insert query on a table of approximatelly 3mln rows, 4 columns. Query is part of every day process, and for same days, the query stucks forever. It's just blocked. It's ...
0
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0answers
257 views

Getting Waiting for table metadata lock for select statements

I am using MySQL server 5.6.23 on CentOS and server configuration is like RAM - 32 GB Cores - 6 cores Innodb buffer pool size = 8 GB Key cache size = 2 GB We are using only select queries. But all ...
0
votes
0answers
107 views

How can I obtain concurrent deletes for this table?

We have a program that is currently doing something to the effect of: SET TRANSACTION ISOLATION LEVEL READ COMMITTED BEGIN TRANSACTION UPDATE [Source].[dbo].[SourceTable] SET [ProcessedOn] = ...
0
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0answers
272 views

Unresponsive MySQL database

I've setup a MySQL server on Ubuntu machine. When running a heavy query (the table has over 1M rows), the database becomes unresponsive. Upon connection it returns: Can't connect to MySQL server ...
0
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0answers
1k views

Why is InnoDB waiting for table metadata lock in simple INSERT/DELETE + SELECT?

I've started using a new MySQL server and moved an InnoDB table there. I'm seeing a weird behavior that when I have a long running INSERT / DELETE, any SELECT from the same table is locked which is ...
0
votes
0answers
100 views

Why does the delete/update block each other in this case?

The following drives me crazy. I have: session1>begin; session2>begin; session2>update dummy set salary=1000 where id=11; session1>delete from dummy where id=1; id is the PK ...
0
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0answers
2k views

Oracle Transaction recovery: lock conflict caught and ignored

In alert log there are a lot of "Transaction recovery: lock conflict caught and ignored" statements. I've found some information, that this error is caused when there is an active dead transaction. ...