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10 Newer Entries Showing entries 91 to 100 of 33326 10 Older Entries
Low-concurrency performance for range queries: MySQL 5.7 vs previous releases
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This is my third post on low-concurrency performance regressions in MySQL 5.7.5 and the focus here is on short range scans. Previous posts were on point queries and sql-bench. This explains performance for 10 and 1000 row index range scans with InnoDB. MySQL 5.7.5 is between 1.49X and 1.63X slower than 5.0.85 for the tested queries with 10 row range scans. It is between 1.37X and 2.67X slower than 5.0.85 for the tested queries with 1000 row range scans. I will save the analysis for another blog post but covering secondary index scans do worse than  PK scans at high concurrency and non-covering secondary queries do the worst. Note also the huge improvement for InnoDB 5.6 and  [Read more...]
MySQL 5.6.21 Overview and Highlights
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MySQL 5.6.21 was recently released (it is the latest MySQL 5.6, is GA), and is available for download here.

For this release, there was 1 “InnoDB Notes” and 1 “Functionality Added or Changed” bug fix (and 0 “Security Fix”), so not much there, but of course they should be noted:

  • InnoDB Note: The –skip-innodb option is now deprecated and its use results in a warning. It will be removed in a future MySQL release. This also applies to its synonyms (–innodb=OFF, –disable-innodb, and so forth).
  • Functionality Added: Internally, spatial data types such as Geometry are represented as BLOB values, so when invoked with the –hex-blob option, mysqldump now displays spatial values in hex. (Bug
  •   [Read more...]
    libAttachSQL Benchmarks With Sysbench
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    This week I have been spending a little bit of time creating a module for Sysbench so that it can use libAttachSQL as a database driver. The reason for doing this is twofold:

  • Brian (my boss at HP's Advanced Technology Group) said now would be a good time to benchmark libAttachSQL
  • I really needed more than a few basic queries to shake out bugs in the library, and a benchmark is a good way to shove a few million through it
  • On the bug front, it did find a total of 5 bugs, a couple of them serious. Which is great, the more testing and bug finding the better. These have all been fixed in GitHub and will be part of the upcoming 0.5.0 release.

    The Test Setup

    To

      [Read more...]
    MySQL Workbench 6.2: New Migration Source and Sync Feature
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    MS Access Migration

    MS Access support was added to the Migration Wizard in MySQL Workbench 6.2, joining MS SQL Server, Sybase ASE, Sybase SQL Anywhere, PostgreSQL, SQLite and “Generic ODBC” as migration sources. You can read more about it in How-To: Guide to Database Migration from MS Access using MySQL Workbench.

    Include Model Scripts in Forward Engineering and Synchronization

    Workbench modeling has always supported attaching SQL script files to the model, usually for documentation/organization purposes. You can now include these attachments to the output script when performing forward engineering or synchronization.

      [Read more...]
    HAProxy: Give me some logs on CentOS 6.5!
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    HAProxy is frequently used as a load-balancer in front of a Galera cluster. While diagnosing an issue with HAProxy configuration, I realized that logging doesn’t work out of the box on CentOS 6.5. Here is a simple recipe to fix the issue.

    If you look at the top of /etc/haproxy/haproxy.cfg, you will see something like:

    global
        log         127.0.0.1 local2
    [...]

    This means that HAProxy will send its messages to rsyslog on 127.0.0.1. But by default, rsyslog doesn’t listen on any address, hence the issue.

    Let’s edit /etc/rsyslog.conf and uncomment these lines:

    $ModLoad imudp
    $UDPServerRun 514

    This will make rsyslog listen on UDP port 514 for all IP

      [Read more...]
    Generated Columns in MySQL 5.7.5
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    Generated Columns is a new feature available in the latest lab release. This work is based on a contribution by Andrey Zhakov. Thanks, Andrey! The Optimizer team modified it to follow the current MySQL design, and to lift a number of limitations.

    The syntax is:

    <type>   [ GENERATED ALWAYS ]   AS   ( <expression> )   [ VIRTUAL|STORED ]
    [ UNIQUE [KEY] ]   [ [PRIMARY] KEY ]   [ NOT NULL ]   [ COMMENT <text> ]

    There are two kinds of Generated Columns: virtual (default) and stored. Virtual means that the column will be calculated on the fly when a record is read from a table. Stored means that


      [Read more...]
    Low-concurrency performance for point lookups: MySQL 5.7.5 vs previous releases
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    My series on low-concurrency performance continues. Previously I compared results for sql-bench and here I use point queries run by mysqlslap for 1, 4 and 32 concurrent clients to compare MySQL versions 5.0, 5.1, 5.5, 5.6 and 5.7 for the InnoDB and Heap storage engines. All binaries (mysqlslap, mysqld) ran on the same host. The test table has 64,000 rows. The test binaries are described here. Compared to MySQL 5.0.85, for the workload with 1 thread:

    • Response time for 5.7.5 is 1.47X worse without the PS and 1.51X worse with the PS
    • Response time for 5.6.21 is 1.37X worse without


      [Read more...]
    libAttachSQL Benchmarks With Sysbench
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    libAttachSQL Benchmarks With Sysbench

    This week I have been spending a little bit of time creating a module for Sysbench so that it can use libAttachSQL as a database driver. The reason for doing this is twofold:

  • Brian (my boss at HP’s Advanced Technology Group) said now would be a good time to benchmark libAttachSQL
  • I really needed more than a few basic queries to shake out bugs in the library, and a benchmark is a good way to shove a few million through it
  • On the bug front, it did find a total of 5 bugs, a couple of them serious. Which is great, the more testing and bug finding the better. These have all been fixed in GitHub and will be part of the upcoming

      [Read more...]
    Dynamic Columns Tutorial – Part 1: Introduction
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    Thu, 2014-10-02 19:21maxmether

    For certain situations, the static structure of tables in a relational database can be very limited. Each column is statically defined, has a pre-defined type and you can only enter a value of that type into the column.You can be creative and list multiple values in one column, but then those values are not generally easily accessed and manipulated with other functions. You have to use an API or contortions of a function like SUBSTRING() to pull out a value you want. Even then, you have to know what is contained in the column to be able to manipulate it properly. These methods can require too much manual intervention to assess and access the data contained in the column.

    If you want to add columns as the information stored in your tables grows and your needs change you need to do fairly expensive ALTER TABLE operations. These have

      [Read more...]
    How to get MySQL 5.6 parallel replication and Percona XtraBackup to play nice together
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    Thu, 2014-10-02 17:25kolbekegel

    MySQL 5.6 introduces a new "multi-threaded slave" feature (aka "parallel replication") that turns the "slave SQL thread" into a number of distinct threads that each apply events to different schemas. This means that separate slave "worker threads" will be executing different positions in the slave's relay log (corresponding, of course, to different positions in the master's binary log) and that the Relay_Master_Log_File and Exec_Master_Log_Pos values in SHOW SLAVE STATUS output are no longer an accurate indicator of the current position of the slave. This causes severe problems if using Percona XtraBackup/innobackupex with the --slave-info option to get a backup that can be used to seed a new slave. Let's take a look at how multi-threaded slave works

      [Read more...]
    10 Newer Entries Showing entries 91 to 100 of 33326 10 Older Entries

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