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Displaying posts with tag: mysql (reset)

A discovery - Index Condition Pushdown can cause a slowdown after all
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MariaDB 5.5 and then MySQL 5.6 got Index Condition Pushdown (ICP) optimization (initially coded by yours truly). The idea of ICP is simple: after reading the index record, check the part of WHERE condition that can be computed using index columns, and only then read the table record. That way, we avoid reading table rows that don’t satisfy index condition:

It seems apparent that ICP can never make things slower. The WHERE clause has to be checked anyway, and not reading certain records can only make things faster.

That was what I thought, too, until recently Joffrey Michaie observed the contrary “in the wild”: we’ve got a real-world case where

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Creating PivotTables when importing MySQL data using MySQL for Excel
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In a previous blog post (Importing related MySQL tables into an Excel Data Model using MySQL for Excel) we covered in detail how an Excel Data Model can be created containing tables and their relationships so the data can be analyzed in Excel via a PivotTable. In this blog post we are going to talk about one of the features included since MySQL for Excel 1.3.0 that allows you to create PivotTables for data imported from MySQL tables, views or stored procedures, or more importantly for the whole Excel Data Model if it is created.

Remember you can install the latest GA or maintenance version using the MySQL Installer or optionally you can download directly any GA or non-GA version from the MySQL Developer Zone.

Low-concurrency performance for updates with InnoDB: MySQL 5.7 vs previous releases
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First I tested updates with the Heap engine as a base case and now I report on InnoDB to find regressions that are specific to it. The workload is described in the previous blog post. Response time is measured at 1, 4 and 32 threads for two types of updates. The unindexed update increments an unindexed column. The indexed update updates a column that is in a secondary index. Tests are run with the binlog enabled and disabled. Tests are done for MySQL versions 5.0.85, 5.1.63, 5.5.40, 5.6.21 and 5.7.5. In some cases tests are also done with the adaptive hash index disabled. The test database has 64,000 rows but all updates are to one row (lots of contention). The client is mysqlslap running on the same host as mysqld. The test server has 40 hyperthread  [Read more...]
MySQL compression: Compressed and Uncompressed data size
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MySQL has information_schema.tables that contain information such as “data_length” or “avg_row_length.” Documentation on this table however is quite poor, making an assumption that those fields are self explanatory – they are not when it comes to tables that employ compression. And this is where inconsistency is born. Lets take a look at the same table containing some highly compressible data using different storage engines that support MySQL compression:


mysql> select * from information_schema.tables where table_schema='test' G
*************************** 1. row ***************************
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Low-concurrency performance for updates and the Heap engine: MySQL 5.7 vs previous releases
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The low-concurrency performance regression evaluation continues after evaluating range queries. This post covers updates with the Heap engine. The Heap engine is used as the base case and the next post has results for InnoDB. The database has 64,000 rows but all updates were for the same row. Tests were done for updates to an indexed and then an unindexed column at 1, 4 and 32 threads. Tests were also repeated with the binlog disabled and then enabled. There are regressions at 1, 4 and 32 threads. The summary is:
  • Response time at 1 thread for 5.7.5 is between 1.55X and 1.67X worse than 5.0.85 
  • Response time at 32 threads for 5.7.5 is between 1.19X and 1.49X worse than 5.0.85 
  • In all cases it is worse in 5.7 than in

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Database Automation - Private DBaaS for MySQL, MariaDB and MongoDB with ClusterControl
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October 9, 2014 By Severalnines

Installing, configuring, deploying databases and performing repetitive administrative tasks are all part of a DBA’s or sysadmin’s job. This can get pretty repetitive and overwhelming if you are part of a centralized IT team, running multiple databases for your organization’s different departments, or a managed hosting provider responsible for setting up and operating databases for external clients. One way to get out of this ‘manual, repetitive task’ business is through a Database as a Service (DBaaS).

DBaaS is a way of delivering database functionality as a service to one or more consumers. A DBaaS platform would provide automated procedures for database deployment, monitoring,

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libAttachSQL Second Beta, After the Sledgehammer
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Last week I blogged about getting sysbench working with libAttachSQL. This was not only an exercise in performance but also the first real test for libAttachSQL.

Before I had done this testing the most the early Alpha and Beta releases of libAttachSQL had gone through is a few basic queries. So, the first thing I did when I got the sysbench driver working was slap it with 1,000,000 queries. It pretty much exploded instantly on that. Over the course of this release I have probably hit it with over 100,000,000 queries and things run a lot smoother.

This has led to today's release of libAttachSQL 0.5.0. As far as changes go this release has the

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Indeed, MySQL 5.7 rocks : OLTP_RO/RW 1-table Benchmarks
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This is the next part of the stories about MySQL 5.7 Performance..

So far, the previous story was about reaching 645K QPS with SQL queries, while in reality it's only a half of the full story ;-) -- because when last year we've reached 500K QPS due a huge improvement on the TRX-list code, the same improvement made a negative impact on the all single-table test workloads..

What happened finally :

  • the new code changes dramatically lowered contention on TRX-list (trx_sys mutex)
  • which is made MDL related locking much more hot..
  • and if one table becomes hot on a

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Testing the Fastest Way to Import a Table into MySQL (and some interesting 5.7 performance results)
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As I mentioned on my last post, where I compared the default configurations options in 5.6 and 5.7, I have been doing some testing for a particular load in several versions of MySQL. What I have been checking is different ways to load a CSV file (the same file I used for testing the compression tools) into MySQL. For those seasoned MySQL DBAs and programmers, you probably know the answer, so you can jump over to my 5.6 versus 5.7 results. However, the first part of this post is dedicated for developers and MySQL beginners that want to know the answer to the title question, in a step-by-step fashion. I must say I

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MariaDB 10.0 on POWER
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Good news for those wanting to run MariaDB on POWER systems, the latest 10.0 bzr tree (as of a couple of weeks ago) builds and runs well!

I recently pulled the latest MariaDB 10.0 from BZR and built it on a POWER8 system in the lab to run some quick tests. The MariaDB team has done some work on getting MariaDB to run on POWER recently, a bunch of which is based off my work on MySQL on POWER.

There’s obviously still some work in progress going on, but my initial results show performance within around 10% of MySQL, so with a bit of work we will hopefully see MariaDB reach performance parity.

One interesting find was the code to account for thread memory usage uses a single atomic variable: this does not scale and does end up showing up on profiles.

I’ll comment more on the code in a future post, but it looks like we will have MariaDB being functional on POWER in an upcoming release.

10 Newer Entries Showing entries 31 to 40 of 16439 10 Older Entries

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