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Search Results for: concurrent transaction

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 …


Lock Escalation and Big Transactions in TokuDB and TokuMX

We have seen TokuDB lock escalation stall the execution of SQL operations for tens of seconds. To address this problem, we changed the lock escalation algorithm used by TokuDB and TokuMX so that the cost …


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 …


Four Benefits of TokuMX Transactions for MongoDB Applications

From the application’s perspective, TokuMX behaves very similarly, if not identically, to MongoDB in many ways. But in one subtle yet important way, on non-sharded clusters, TokuMX is different. With MongoDB, operations on each single …


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 …


Interactive Debugging of Transaction Conflicts with TokuDB

I am developing a concurrent application that uses TokuDB to store its database. Sometimes, one of my SQL statements returns with a ‘lock wait timeout exceeded’ error. How do I identify the cause of this …


More on MySQL transaction descriptors optimization

Since my first post on MySQL transaction descriptors optimization introduced in Percona Server 5.5.30-30.2 and a followup by Dimitri Kravchuk, we have received a large number of questions on why the benchmark results in both …


MongoDB Transactions? Yes

People claim that MongoDB is not transactional. It actually is, and that’s a good thing. In MongoDB 2.2, individual operations are Atomic. By having per database locks control reads and writes to collections, write operations …


How MySQL Query Cache works with Transactions

As MySQL Manual Says Query Cache works with transactions with Innodb tables but it does not tell you how and with which restrictions. According to my tests it works but it is very restricted and …


MVCC: Transaction IDs, Log Sequence numbers and Snapshots

MySQL Storage Engines implementing Multi Version Concurrency Control have several internal identifiers related to MVCC. I see a lot of people being confused what they are and why they are needed so I decided to …