Questions tagged [lock-escalation]
The lock-escalation tag has no usage guidance.
24 questions
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Does PostgreSQL have lock promotion or escalation?
We having this strange behaviour with ExclusiveLock in one of our database running PostgreSQL 13. I am not able to dig what leads to this lock as lock info is from a monitoring tool.
From what I see ...
- 393
8
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2
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558
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Blocking between two MERGE queries inserting into the same table
Scenario
I have a large table partitioned on an INT column. When I run two different MERGE statements on two different partitions of this table, they seem to be blocking each other.
Sample code to ...
- 707
2
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1
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172
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When Page Lock happen under Read Committed Isolation level in SQL Server
I have a clustered index table in Azure SQL Database. After checking the dm_db_index_operational_stats, the column page_lock_wait_count greater than 0 means there are some Page Lock happended for this ...
- 23
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636
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Why does parallelism cause lock escalation and where is the tipping point?
I use the customized Stack Overflow database (180GB) and run a simple update query: (there is only a clustered index on the Users table)
Begin Tran
Update U set U.Reputation=100000
from StackOverflow....
0
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1
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2k
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Deadlocks caused due to Keylocks and Pagelocks
I have a database on which select, update and insert queries are run.
At times it gave me deadlocks (key locks) while updating and selecting data from the table, it considered the select query to be ...
- 105
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342
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Table Lock Escalation - Performance Questions
I have few questions on table lock escalations, please confirm or disprove:
Index Scan operator in a query results in Table Lock Escalation ? always or not (small tables) ?
When Shared lock is ...
- 5,964
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197
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Does SQL Server upgrade to table locks at total locks or session locks?
I’ve a table that both has mass sequential inserts at the end of the CI and random (very distributed) reads+updates. Naturally, the mass inserts should not block the random access. RCSI is used, so ...
- 205
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2
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91
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lock escalation issue when using DDL trigger
I have a problem, I am trying to create a log table for my database so I can keep track of changes. I have created the following trigger that runs when a table is altered, created and dropped:
CREATE ...
- 11
4
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13k
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What is Postgres lock behaviour when UPDATE WHERE clause does a table scan?
Say you have a large table with tens of millions of rows.
You want to UPDATE large_table SET col=value WHERE col=other_value... but col is not indexed and an EXPLAIN shows that this query will perform ...
- 528
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2k
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How to avoid Table Lock Escalation?
I've got a task to update 5 million rows in a production table, without locking down the whole table for extended time
So, I used approach that helped me before many times - updating top (N) rows at a ...
- 5,964
5
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525
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Lock Escalation and Count Discrepancy in lock_acquired Extended Event
I'm trying to understand why there is a discrepancy in lock count in sys.dm_tran_locks and sqlserver.lock_acquired extended event in certain cases. Here is my repro script, I'm using the ...
- 512
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SQL Server Lock Escalation clarity required
I want to know whether Enabling the Trace Flag 1211 globally prevents the Lock Escalation even in the event of the Huge Memory Pressure.
I have 2 Questions regarding this:-
After Enabling Trace Flag ...
2
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2
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1k
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What type of locks does BEGIN TRANSACTION cause against a specific table that's being read from?
In the following example, what kinds of locks are generated from the explicit transaction block that wraps the SELECT INTO query?
BEGIN TRANSACTION T1
SELECT Field1, Field2, Field3
INTO TableB
FROM ...
- 39.5k
1
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122
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MSSQL - Lock escalation on partitioned indexed view
I'm using partitioned tables where I set LOCK_ESCALATION to AUTO to prevent lock escalation to table level, but keep it on partition level.
On the top of that table I have indexed view which is ...
- 345
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2k
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Queries from different tables locking each other (LCK_M_X)
Background: Was hired to work with JMeter for performance testing but I'm also getting more and more into SQL performance (because of time, and because I like it). I still suck, and will for a long ...
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Why Table Lock Escalation is happening in my scenario
I have a table Table1 that is updated in small chunks using below query:
update top (1000) Table1
set VarcharColumn1 = 'SomeValue'
from Table1
where ID in (select ID from Table2)
and ...
- 5,964
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232
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DeadLock - Two Process Locked Same Index
We have met a scenario that two process acquired exclusive lock on same index ans the same time two are requesting for shared lock to other process which eventually leads to dead lock.
I am still not ...
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6k
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Indexes with High Lock waits - how to fix
I've been running dbo.sp_BlitzIndex and have 4 somewhat similar indexes on the main table in my database. Each one has a high number of waits and escalation attempts. I'm not sure where these are ...
- 75
2
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2
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347
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Handle concurrency on Sql Server to modify specific column
I have table that suffers from racing condition and I don't know how to fix it. I can't solve it 100% in code, so I need the server to help me.
The scenario
Admins of a system may accept or reject ...
- 235
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1
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12k
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Risk of disabling page locking
In another question a user asks how to force row level locking. The answer that he receives tell them how to force row level locking by altering the table and the indexes. The user that answered the ...
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2
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SQL Server 2008 - get current LOCK_ESCALATION on particular table
Is there a way to find the current setting for LOCK_ESCALATION on particular table? Can it be found through system views?
- 428
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1
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Why isn't partition-level lock escalation the default?
In SQL Server, locks are normally escalated from row or page -> table. Starting with SQL Server 2008, a new level of lock escalation was added - partition level.
However, this isn't automatically ...
- 1,228
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can I resolve a deadlock with the rowlock hint?
I have a large delete stored proc and I've reproduced a deadlock in a situation where the deletes would not have deleted anything.
It looks like the part of the stored proc that hit a deadlock was ...
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4
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What is lock escalation?
I was asked this question at an interview and had no answer. Can anyone here explain?
Kilhoffer