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Search Results for: transaction level

Differences between READ-COMMITTED and REPEATABLE-READ transaction isolation levels

As an instructor with Percona I’m sometimes asked about the differences between the READ COMMITTED and REPEATABLE READ transaction isolation levels.  There are a few differences between READ-COMMITTED and REPEATABLE-READ, and they are all related …

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InnoDB locks and deadlocks with or without index for different isolation level

Recently, I was working on one of the issue related to locks and deadlocks with InnoDB tables and I found very interesting details about how InnoDB locks and deadlocks works with or without index for different Isolation levels. …

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Innodb transaction history often hides dangerous ‘debt’

In many write-intensive workloads Innodb/XtraDB storage engines you may see hidden and dangerous “debt” being accumulated – unpurged transaction “history” which if not kept in check over time will cause serve performance regression or will …

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Percona Server: Thread Pool Improvements for Transactional Workloads

In a previous thread pool post, I mentioned that in Percona Server we used an open source implementation of MariaDB’s thread pool, and enhanced/improved it further. Below I would like to describe some of these …

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Introducing TokuMX Transactions for MongoDB Applications

Since our initial release last summer, TokuMX has supported fully ACID and MVCC multi-statement transactions. I’d like to take this post to explain exactly what we’ve done and what features are now available to the …

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A TokuDB Stall Caused by a Big Transaction and How It was Fixed

One of our customers sometimes observed lots of simple insertions taking far longer than expected to complete. Usually these insertions completed in milliseconds, but the insertions sometimes were taking hundreds of seconds. These stalls indicated …

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MongoDB Multi-Statement Transactions? Yes We Can!

Earlier, I talked about the transactional semantics we are introducing to MongoDB. As I hinted at the end of the post, we are actually doing more. We are introducing multi-statement transactions. That’s right, multiple queries, …

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Flexviews is a working scalable database transactional memory example

http://Flexvie.ws fully implements a method for creating materialized views for MySQL data sets. The tool is for MySQL, but the methods are database agnostic. A materialized view is an analogue of software transactional memory. You …

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Innodb undo segment size and transaction isolation

You might know if you have long running transactions you’re risking having a lot of “garbage” accumulated in undo segment size which can cause performance degradation as well as increased disk space usage. Long transactions …

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