53 questions
1
vote
1
answer
80
views
Database concurent UPDATE and SELECT with Read Uncommitted
I have this TABLE_A:
id
columnA
columnB
1
oldValueA
oldValueB
When two queries are performed at the exact same time and concurrency issues arise:
Query #1:
UPDATE TABLE_A
SET columnA = 'newValueA', ...
- 63
0
votes
0
answers
35
views
Can `select` in reads a partially updated row in MySQL with the Read Uncommited isolation level?
Suppose the following two statements are executed in parallel:
-- before: col1=val1, col2=val2
UPDATE my_table SET col1=new_val1,col2=new_val2 WHERE col3=val3
SELECT col1,col2 FROM my_table WHERE ...
- 9,614
0
votes
1
answer
2k
views
Using Entity Framework Core v8.0.8 DbContext and TransactionScope to read uncommitted from a table
I'm currently looking at upgrading a .NET project (standard moving to .NET 8) that uses Entity Framework (v6.4.4) to EF Core (v8.0.8).
For the most part the experience has been painless but I have one ...
- 1
0
votes
1
answer
271
views
How. to read or retry the process for uncommited message in kafka
lets say i am getting 1 to 15 messages from kafka. I am processing it and commiting it, if the message does satisfy the condition I am uncommiting the particular message.
Now, My question is how to ...
- 1
0
votes
0
answers
1k
views
Transaction isolation READ_UNCOMMITED doesn't work
I have written an application using Springboot 2.0 to store books catalog in MySQL 8 database. Book information is being read from the file.
Book object has a list of authors as there can be more than ...
- 596
0
votes
0
answers
405
views
Forgot WITH (READUNCOMMITTED) in SQL
At my company I was advised to always run SQL queries as follows:
SELECT col1, col2
FROM table WITH (READUNCOMMITTED)
WHERE table.id = my_id;
It is a production database which is used by other ...
- 2,146
-1
votes
1
answer
194
views
Uncommitted event is not received in the next poll
I have a consumer with max.poll.records set to 1 and enable.auto.commit set to false for the manual offset control. However even when I am not calling commitSync, the subsequent poll is returning next ...
- 21
0
votes
0
answers
71
views
Spring Data JPA isolationlevel does not affect on SQLServer queries
I have a @Service layer class with several methods, which have @Transactional(isolation = Isolation.READ_UNCOMMITTED) annotated queries and @Transactional annotated write transactions.
Sometime ...
0
votes
0
answers
44
views
Predicate CONTAINS doesn't return records with NOLOCK
I am writing integration tests and I use TransactionScope(TransactionScopeAsyncFlowOption.Enabled) for this purpose.
I add some data to DB (MS SQL Server) and then check the result, compare it etc.
...
- 23
0
votes
1
answer
958
views
EF Read-Uncommitted for all select queries
Since I'm having very long-lasting lock issues on my table records...
would it be correct to use the "Read-Uncommitted" transaction isolation level for all select queries of Entity Framework ...
- 129
1
vote
2
answers
7k
views
How can we set the Read Uncommitted isolation level with JPA and Hibernate?
In he famous book "Java persistence with Hibernate" we can read the following:
"A persistence context is a cache of persistent entity instances.... Automatic dirty checking is one of ...
- 1,469
1
vote
1
answer
1k
views
Postgres - killing uncommitted transaction
I have read of a few ways to do this (namely, querying the pg_stat_activity table to get the pid to kill), but I have no data coming back in those queries.
In other DBMSs like MSSQL, I could at least ...
- 326
1
vote
2
answers
425
views
Can ReadUncommitted know all LOWER auto-increment IDs that will exist?
Suppose we have a table with an auto-increment primary key. I want to load all IDs greater than the last ID I have seen.
SELECT id
FROM mytable
WHERE id > 10;
With the naive approach, I risk ...
- 8,873
2
votes
1
answer
1k
views
A recognition error occurred when nolock is used in hibernate query
I have simple hibernate query with nolock used in query. I am getting error - A recognition error occurred and hibernate error is Exception thrown: 'NHibernate.Hql.Ast.ANTLR.QuerySyntaxException' in ...
- 1,293
0
votes
0
answers
830
views
How to read uncommitted data from other table inside trigger
I have 2 tables, Contact and ContactFunction. They have a One to Many relationship, as in a Contact can have many ContactFunctions. So ContactFunction has ContactID as a foreign key. So in my .NetCore ...
0
votes
1
answer
350
views
MySQL dirty reads vs dirty reads defined in SQL standard
From MySQL manual:
READ UNCOMMITTED
SELECT statements are performed in a nonlocking fashion, but a possible earlier version of a row might be used. Thus, using this isolation level, such reads are ...
- 366
6
votes
4
answers
9k
views
Read Committed vs Read Uncommitted if both transactions do not rollback
I am trying to understand read committed and read uncommitted isolation levels. I know that theoreticay read uncommitted allows dirty reads and read committed doesn't, but I still can't really ...
- 61
0
votes
1
answer
2k
views
How to verify TransactionScope works with MySQL?
I want to add read uncommitted isolation level.i know it is possible to do with SQL statement. but I want to try with TransactionScope and I tried but not getting any isolation statements on MySQL ...
- 170
0
votes
1
answer
2k
views
Running stored procedure in a SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED
I setup a DbContext where I have this code:
base.Database.ExecuteSqlCommand("SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;");
in the context constructor. I execute a stored procedure like this:
...
- 191
0
votes
0
answers
76
views
SqlXml throws NullReferenceException
I have a trouble. :(
MS SQL Server 2016 13.0.15900.1
.NET Framework 4.5.2
There is a table with large xml fields (> 1 mb)
A terrible procedure which read, change and update [xmlField] with(out) XPath
...
- 210
1
vote
1
answer
584
views
Read uncommited rows created by postgresql function?
I wrote a function that creates a row in the table mytable accordingly to the parameters and returns the id of the created row.
Unfortunately, if I use the following statement, the SELECT returns no ...
- 7,391
0
votes
0
answers
48
views
Sql Server read uncommitted field level variance?
If my connection allows dirty reads, is it possible that I would get inconsistent results from multiple fields of the same row? Example:
Connection 1:
Update table1 set col1 = 1, col2 = 1 where ...
- 3,248
5
votes
3
answers
7k
views
EF6 with TransactionScope - IsolationLevel.ReadUncommitted but got ReadCommitted first
There is a performance and lock issue when using EF for a update-from-query case on MSSQL 2008. So I put ReadUncommitted transaction isolationlevel, hoping to resolve it, like this,
Before
using (...
- 735
1
vote
0
answers
1k
views
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED on insert record
Consider the following SQL statement:
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED
BEGIN TRANSACTION
insert into Customer(name)
values('CustomerName')
COMMIT
Am I right in saying this Isolation ...
- 1,122
0
votes
1
answer
8k
views
SET TRANSACTION isolation level READ uncommitted - is it necessary to explicitly use transaction begin and end?
Does this query below work or do I have use explicitly transaction being and end?
Yes I know the dangers of the read uncommitted
SET TRANSACTION isolation level READ uncommitted
SELECT TOP 100 ...
- 24k
4
votes
1
answer
44k
views
Oracle SQL: NOLOCK in join statment
I can not use NOLOCK after table names in join statements.
Is it even a valid scenario to try to read uncommitted data over JOINs
1
vote
0
answers
699
views
Uncommitted Transaction Isolation Level
I am trying to understand how Transactions work in c# using the TransactionScope object. I have an understanding about them in SQL server but I don't know how to verify this in c#. For example I want ...
- 1,819
1
vote
2
answers
1k
views
SQL Server long running transaction
I am wondering how resource expensive it is to perform a begin transaction on a connection and immediately update/insert a row into a database and leave this transaction hanging for several hours.
...
- 1,826
3
votes
1
answer
951
views
How does MySQL InnoDB implement Read Uncommitted isolation level
Oracle doesn't allow dirty reads, so Read Uncommitted is not even allowed to be set from JDBC.
PostgreSQL also falls back to Read Committed, when choosing Read Uncommitted.
SQL Server defines a ...
- 156k
1
vote
2
answers
107
views
How don't submit in a database but select the modified data
I have a database with multiple tables
and the user can change the data in the table.
my problems is that I wont that nothing changes in the database until the user click the button "save", and even ...
- 129
0
votes
1
answer
868
views
SQL Server Isolation level real world example
Let's say we need to develop a bidding application such as one in eBay. We don't want one user's bidding to block another user's bidding, which will result in slow response. Also, when I place a bid ...
- 2,022
1
vote
0
answers
139
views
NOLOCK at query level
I've a query to run a SQL server table, in which, I am not concerned with the exact count. So, I want to specify NOLOCK for that query. But, query itself consists of multiple subqueries and multiple ...
- 794
0
votes
1
answer
107
views
Why does 'read uncommited' isolation level allow locks?
I put a breakpoint in my code to pause the execution before transaction is commited or rolled back. Then I'd like to see the current state of the database, but when I set in ssms the transaction ...
- 14k
5
votes
1
answer
13k
views
How to set isolation level in @Transactional "READ_UNCOMMITTED". I am using EclipseLink 2.5.1-RC1
I have a requirement to start new Transaction within an ongoing Transaction so that an exception in 2nd transaction will rollback only new transaction not the old one.
This I am doing by setting ...
- 265
0
votes
1
answer
378
views
SQL Server Update Locks
If you have the following sql, is it possible that if it is run multiple times by many different processes at exactly the same time, that two or more processes may update the table?
SET TRANSACTION ...
- 1,003
4
votes
1
answer
2k
views
Can't see rows inserted by a running transaction when isolation level is READ_UNCOMMITTED
I have applications that insert rows into table A concurrently. Each application inserts rows in batch mode (using a JDBC prepared statement) using a single transaction per batch (to avoid rebuilding ...
- 7,109
0
votes
1
answer
2k
views
How to read uncommitted data in nHibernate transaction?
I would like to know to know how to read uncommitted data. I have an application which is saving an entry into table1 and then tries to read some entry from same table. I am unable to do that because ...
- 3,101
1
vote
3
answers
5k
views
Could an query with READ UNCOMMITTED isolation level cause locks on the tables it access?
My app needs to batch process 10M rows, the result of a complex SQL query that join tables.
I'll plan to be iterating a resultset, reading a hundred per iteration.
To run this on a busy OLTP ...
- 5,638
0
votes
1
answer
2k
views
Read modified and yet uncommitted data
select .. WITH UR ignores locks and gives only currently committed data
how to read data that are not committed ?
as in Oracle :
update table set ..
select .. gives modified and yet uncommitted ...
- 328
0
votes
1
answer
179
views
NHibernate: populate list with uncommitted data related only by FK in database
This is an elaboration and clarification of this question.
Suppose I have two tables, Foo and Bar.
Bar has a FK to Foo.
In the application, the tables are represented by classes and Foo has a list ...
- 169
4
votes
1
answer
4k
views
SQL Server Read Uncommitted is blocking transactions
I have a work queue in SQL, managed by some services that read out entries to process with READPAST queries.
I recently added a UI to check on queue status that uses READ UNCOMMITTED NHibernate ...
- 9,641
1
vote
2
answers
738
views
Read uncomitted data from HasMany-relationship with NHibernate
I have an NHibernate map which defines a HasMany-relationship on a type, i.e. a class has a list of another class.
I would like NHibernate to be able to read uncommitted data including the list ...
- 169
7
votes
1
answer
10k
views
"SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED" not taking? Or am I looking in the wrong way?
We have a problem with some database code that apparently executes with the wrong isolation level. In this particular part of the code, it is supposed to execute with "READ UNCOMMITTED" to minimize ...
- 394k
0
votes
1
answer
165
views
Read uncommitted when using Rob Conery's Massive
Is there a way to do a read uncommitted when using Rob Conery's Massive without writing your own query?
It is for a site that is mostly read-only. A CMS type of a site.
- 6,301
8
votes
2
answers
2k
views
In MySQL Why does setting a variable from a select acquire a lock when using read uncommitted?
We have a table in MySQL using InnoDB, and we are using a transaction isolation level of read uncommitted. Why does setting @x as shown acquire a lock?
mysql> set @x = (select userID from users ...
- 925
0
votes
2
answers
1k
views
Delete an uncommitted inserted row in DB2 (V8.2.7 - Fix 14)
Upon client's request, I was asked to turn a web application on read-uncommitted isolation level (it's a probably a bad idea...).
While testing if the isolation was in place, I inserted a row ...
7
votes
2
answers
7k
views
Reading uncommitted changes (dirty read) from SQLite
I wrote an application (using Qt in C++) which inserts data into a SQLite database. Another application reads data from the same database, but I noticed that it is not possible to read uncommitted ...
- 10k
0
votes
2
answers
426
views
READ UNCOMMITTED and Estimates
From time to time, I want to run a stored procedure to get a rough estimate of how many records in two or three different tables satisfy some criteria. If during this estimate new records are added, ...
- 563
3
votes
1
answer
11k
views
How set transaction isolation level to ReadUncommitted in SQLite?
According to the answer on this post it states:
Did you know that ReadUncommitted will revert to Serialized isolation unless you've enabled the shared cache and both connections are from the same ...
- 6,406
1
vote
0
answers
501
views
Getting Uncommitted Transactions Sqlite With System.Data.Sqlite
I am trying to get a count of uncommitted records in a SQLite database using the System.Data.Sqlite library. My research thus far has pointed towards using the PRAGMA read_committed, but I always get ...
- 7,045