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Displaying posts with tag: Features (reset)
Online ALTER TABLE in MySQL 5.6

This is the low-level view of data dictionary language (DDL) operations in the InnoDB storage engine in MySQL 5.6. John Russell gave a more high-level view in his blog post April 2012 Labs Release – Online DDL Improvements. MySQL before the InnoDB Plugin

Traditionally, the MySQL storage engine interface has taken a minimalistic approach to data definition language. The only natively supported operations were CREATE TABLE, DROP TABLE and RENAME TABLE. Consider the following example:

INSERT INTO t VALUES (1),(2),(3);

The CREATE INDEX statement would be executed roughly as follows:

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New Enhancements for InnoDB Memcached

In MySQL 5.6, we continued our development on InnoDB Memcached and completed a few widely desirable features that make InnoDB Memcached a competitive feature in more scenario. Notablely, they are

1) Support multiple table mapping

2) Added background thread to auto-commit long running transactions

3) Enhancement in binlog performance

 Let’s go over each of these features one by one. And in the last section, we will go over a couple of internally performed performance tests.

Support multiple table mapping

In our earlier release, all InnoDB Memcached operations are mapped to a single InnoDB table. In the real life, user might want to use this InnoDB Memcached features on different tables. Thus being able to support access to different table at run time, and having different mapping for different connections becomes a very desirable feature. And in this GA release, we allow …

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InnoDB Compression Improvements in MySQL 5.6

MySQL 5.6 comes with significant improvements for the compression support inside InnoDB. The enhancements that we'll talk about in this piece are also a good example of community contributions. The work on these was conceived, implemented and contributed by the engineers at Facebook. Before we plunge into the details let us familiarize ourselves with some of the key concepts surrounding InnoDB compression.

  • In InnoDB compressed pages are fixed size. Supported sizes are 1, 2, 4, 8 and 16K. The compressed page size is specified at table creation time.
  • InnoDB uses zlib for compression.
  • InnoDB buffer pool will attempt to cache compressed pages like normal pages. However, whenever a page is actively used by a transaction, we'll always have the uncompressed version of the page as well i.e.: we can have a page in the buffer pool in compressed only form or in a state where we have both the compressed page …
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Optimizing neighbor flush behavior

Note: this article was originally published on on April 16, 2012 by Yasufumi Kinoshita.

The performance of flush_list flushing of InnoDB decides the basic performance for modifying workloads. So, it is important to optimize the flush behavior. In this post we’ll consider how to optimize the neighbor-flushing behavior.

Factor 1: Characteristics of storage

Depending on the characteristics of your storage’s throughput for write IO, you can term your storage as either “write amount bound” or “write times bound”. The minimum unit of the InnoDB datafile is page size (16KB or less). And InnoDB attempts to combines them in a single IO up to 1 extent (1MB) maximum, if they are contiguous.

<one HDD>:  Almost “write times bound”. Because head-seek time is the most …

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New flushing algorithm in InnoDB

Note: this article was originally published on on April 13, 2012 by Inaam Rana.

In MySQL labs release April 2012 we have reworked the flushing heuristics in InnoDB. In this post I’ll give an overview of what we have changed and the various configuration variables we have introduced to fine tune the flushing algorithm. If you are interested in finding out how our new flushing algorithm fares in benchmarks you can get these details in Dimitri’s well-explained blog here.

Flushing means writing dirty pages to disk. I have explained in some detail about adaptive_flushing and …

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InnoDB persistent stats got a friendly UI

Note: this article was originally published on on April 11, 2012 by Vasil Dimov.

After introducing InnoDB persistent statistics in MySQL 5.6, in this April Labs release we have dressed it up in a nice UI and refactored the internals a bit to make the code more elegant and straight-forward.

The persistent stats are now controlled globally and can also be overridden at table level, should any table require a different behavior.


The server global flag –innodb-stats-persistent (boolean) now controls whether all InnoDB tables use persistent statistics or not. Keep in mind that if a table is using persistent stats then its statistics will not be updated automatically and you are responsible for …

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Memcached With SASL Support

Note: this article was originally published on on April 11, 2012 by Jimmy Yang.

In this April MySQL Lab release, we’ll provide you a more robust and release-ready InnoDB Memcached Engine with a few enhancements. The most notable addition is the SASL support, which gives users the capability to protect their MySQL database from unauthenticated access through memcached clients. In this blog, I will walk you through steps of getting this option enabled.

Background Info:
SASL stands for “Simple Authentication and Security Layer”, which is a Standard for adding authentication support to connection-based protocols. Memcached added SASL support starting its 1.4.3 release. And here is a good article that gives you some background on why …

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April 2012 Labs Release – Online DDL Improvements

Note: this article was originally published on on April 11, 2012 by John Russell.

This feature is a continuation of the “Fast Index Creation” feature introduced in Fast Index Creation in the InnoDB Storage Engine. Now you can perform other kinds of DDL operations on InnoDB tables online: that is, with minimal delay for operations on that table, and without rebuilding the entire table. This enhancement improves responsiveness and availability in busy production environments, where making a table unavailable for seconds or minutes whenever its …

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InnoDB transportable tablespaces

Note: this article was originally published on on April 10, 2012 by Sunny Bains.

The Problem

In the past, users were unable to take full advantage of the FLUSH TABLES WITH READ LOCK statement. InnoDB simply ignored the flush to disk part. If the table did not have any dirty pages in the InnoDB buffer that weren’t synced to disk (due to sheer luck) then it was safe to copy the .ibd file to another location. Also, the restore was not without its limitations and complications. The .ibd file could not be copied over to another server because InnoDB during import did not fix up metadata required for a trouble-free import. The main problems during …

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Choose the Location of your InnoDB File-per-Table Tablespace

Note: this article was originally published on on April 10, 2012 by Kevin Lewis.

The April 2012 InnoDB labs release introduces a new feature in InnoDB that allows you to choose the location of specific tables.  For example, you can place critical tables onto an SSD drive while leaving the system tablespace on a hard drive.  Conversely, you can store you primary database files on an SSD and put a seldom used but very large archive or reference table on a larger cheaper hard drive.

Innodb now makes use of the following existing syntax in MySQL ;

CREATE TABLE  . . .  DATA DIRECTORY = ‘absolute path of data directory’;

CREATE TABLE  . . .  PARTITION . . . DATA DIRECTORY = ‘absolute path of data directory’;

This syntax is used in MyISAM and Archive engines to make use …

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