November 25, 2014

Innodb redo log archiving

Percona Server 5.6.11-60.3 introduces a new “log archiving” feature. Percona XtraBackup 2.1.5 supports “apply archived logs.” What does it mean and how it can be used? Percona products propose three kinds of incremental backups. The first is full scan of data files and comparison the data with backup data to find some delta. This approach […]

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 posts look rather different. We were curious as well, so we tried to answer that question by retrying benchmarks on […]

Measuring the amount of writes in InnoDB redo logs

Choosing a good InnoDB log file size is key to InnoDB write performance. This can be done by measuring the amount of writes in the redo logs. You can find a detailed explanation in this post. To sum up, here are the main points: The redo logs should be large enough to store at most […]

How InnoDB handles REDO logging

Xaprb (Baron) recently blogged about how InnoDB performs a checkpoint , I thought it might be useful to explain another important mechanism that affects both response time and throughput – The transaction log.

MySQL Limitations Part 2: The Binary Log

This is the second in a series on what’s seriously limiting MySQL in certain circumstances (links: part 1). In the first part, I wrote about single-threaded replication. Upstream from the replicas is the primary, which enables replication by writing a so-called “binary log” of events that modify data in the server. The binary log is […]

Analyzing the distribution of InnoDB log file writes

I recently did a quick analysis of the distribution of writes to InnoDB’s log files. On a high-traffic commodity MySQL server running Percona XtraDB for a gaming workload (mostly inserts to the “moves” table), I used strace to gather statistics about how the log file writes are distributed in terms of write size. InnoDB writes […]

SSD, XFS, LVM, fsync, write cache, barrier and lost transactions

We finally managed to get Intel X25-E SSD drive into our lab. I attached it to our Dell PowerEdge R900. The story making it running is worth separate mentioning – along with Intel X25-E I got HighPoint 2300 controller and CentOS 5.2 just could not start with two RAID controllers (Perc/6i and HighPoint 2300). The […]

Impact of logging on MySQL’s performance

Introduction When people think about Percona’s microslow patch immediately a question arises how much logging impacts on performance. When we do performance audit often we log every query to find not only slow queries. A query may take less than a second to execute, but a huge number of such queries may significantly load a […]

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 take a time to explain it a bit. This is general explanation, it does not corresponds to Innodb in particular […]

Choosing proper innodb_log_file_size

If you’re doing significant amount of writes to Innodb tables decent size of innodb_log_file_size is important for MySQL Performance. However setting it too large will increase recovery time, so in case of MySQL crash or power failure it may take long time before MySQL Server is operational again. So how to find the optimal combination […]