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4
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1answer
59 views

Why would MySQL request a shared-lock after setting transaction level to READ UNCOMMITTED

Running a processing job in multiple parallel batches which basically reads big chunks of rows to update a few - it's OK here to use a lower transaction level since I know the relevant values won't be ...
1
vote
1answer
92 views

What are the considerations when using SERLIALIZABLE over READ COMMITTED isolation level in Oracle?

What are the considerations when using SERIALIZABLE isolation level over the default READ COMMITTED in an Oracle database? Given the concurrency system used within Oracle (using transaction logs to ...
0
votes
1answer
34 views

Which isolation level do I need?

I've read a lot of articles about Isolation levels, but I'm confused which one to choose for my MySQL 5.6 database. This is my situation: Let's say I have two group of users: Group A (...
0
votes
1answer
528 views

Sybase ASE lock table to disallow users insert values

I need to disallow users to insert values in some table, for example for a 5 mins. Seems I should use at isolation clause but can't figure out how to use it. Thanks
1
vote
0answers
56 views

NOLOCK vs Read Uncommitted

in our environment, reports are running on the subscriber and resulting in deadlocks with MS Replication SPs, which are doing inserts/updates. What's the best way to eliminate the deadlocks? We have ...
1
vote
0answers
182 views

debugging PostgreSQL serialization failures

I am trying to migrate our PostgreSQL 9.4 database from transaction level READ COMMITTED to either REPEATABLE READ or SERIALIZABLE. In either case, I'm exposed to a new set of errors with the format: ...
1
vote
0answers
62 views

Can a slow SELECT statement in READ COMMITTED isolation level read content from concurrent committed UPDATE?

Let's say we have a big table with hundreds of million of rows (or more). On one connection, we perform a query requiring full table scan under READ COMMITTED isolation level: SELECT * FROM bigtable;...
1
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0answers
34 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 ...
1
vote
0answers
173 views

Transactions using Isolation Level on databases with FileStream

We have a highly transactional application. We have a requirment to upload huge data into our database that can happen for a duration of 5-10 minutes. During our upload time, the tables are getting ...
0
votes
0answers
13 views

Isolation Level Impact on Selecting a Row Moving Between Two Tables

I have two tables (identical structure, one for current data and one for archive) being used as a source for a datamart staging table. I construct a SSIS data flow that runs SELECTs on both tables ...
0
votes
0answers
35 views

How system resolves when particular resource lock at uncommitted transaction

Let us assume Transaction T1#: Initiated on 2015-10-30 10:25:41.380 Transaction T2#: Initiated on 2015-10-30 10:25:41.580 The above two transactions are initiated through application. T1# & ...
0
votes
0answers
22 views

Does DB2 for z/OS have isolation level similar to READ ONLY in Oracle?

Does DB2 for z/OS have isolation level similar to READ ONLY in Oracle? I need to implement several big selects to DB2 and also I need to retrieve consistent data which was commited on time when ...
0
votes
0answers
275 views

What are the possible reasons for SQL Server errors on reading operations upon switching ALLOW_SNAPSHOT_ISOLATION` and `READ_COMMITTED_SNAPSHOT ON?

I have a client-server app running in Windows Server 2008R2 using/interacting SQL Server 2012. After reading app's documentation as well as feedbacks on internet from those who already accomplished ...
0
votes
0answers
81 views

MySQL server vs client isolation levels

What is the difference between setting the transaction isolation level in the client configuration and the server configuration? If I set the client isolation level to be serializable while the server'...
0
votes
0answers
164 views

What would this non-'unique index with a unique search condition` query lock?

I am not sure about this part of the transaction manual For locking reads (SELECT with FOR UPDATE or LOCK IN SHARE MODE), UPDATE, and DELETE statements, locking depends on whether the statement ...