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Showing entries 1 to 10 of 33604 10 Older Entries
Improvements for XA in MySQL 5.7
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Today I was doing some tests with XA transactions in MySQL 5.6.

The output of the XA RECOVER command to list transactions was hard to read because of the representation of the data column:

The good news is that 5.7 has transaction information in performance_schema:

mysql> select trx_id, isolation_level, state, xid, xa_state, access_mode 
-> from performance_schema.events_transactions_current; …





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Querying InnoDB Tables
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Somebody ran into the following error message trying to query the innodb_sys_foreign and innodb_sys_foreign_cols tables from the information_schema database:

ERROR 1227 (42000): Access denied; you need (at least one of) the PROCESS privilege(s) for this operation

It’s easy to fix the error, except you must grant the process privilege. It’s a global privilege and it should only be granted to super users. You grant the privilege global PROCESS privilege to the student user with the following command:

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How to handle wrong page type in external pages
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First step of successful MySQL data recovery is to find InnoDB pages with your data. Let’s call it first, because prerequisite steps are already done.

InnoDB page type is a two bytes integer stored in the header of a page. For MySQL data recovery two are important:

  • FIL_PAGE_INDEX. Pages of this type are nodes of B+ Tree index where InnoDB stores a table.
  • FIL_PAGE_TYPE_BLOB. So called external pages, where InnoDB keeps long values of BLOB or TEXT type.

stream_parser

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Best Howto posts on Scalable Startups
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Join 28,000 others and follow Sean Hull on twitter @hullsean. MySQL slow query on RDS If you run MySQL as your backend datastore is there one thing you can do to improve performance across the application?. Those SQL queries are surely key. And the quickest way to find the culprits is to regularly analyze your […]

Happy Holidays and Best Wishes for 2015!
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We would like to wish you a happy holidays on behalf of the DBAHire.com team. May all your dreams come true in 2015!

Photograph taken at the Christmas market of Valencia (Spain) in December 2014.

May your MySQL innodb_buffer_pool_reads be low and your Uptime high in 2015.

MySQL versions performance comparison
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Introduction

 

This blog aims to make a performance comparison between the different MySQL versions/editions and also comparing the differents MySQL forks such as Percona Server and MariaDB.  Indeed number of improvements as been done to innodb storage engine in the last MySQL versions. You can find below some of the performance improvements applied to InnoDB these last years (non exhaustive list):


MySQL 5.0:


1. New compact storage format which can save up to 20% of the disk space required in previous MySQL/InnoDB versions.
2. Faster recovery from a failed …



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OurSQL Episode 203: Scaling by Proxy Part 2
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PodcastsLearningPerformanceServer Tuning

In this episode we finish our series on MaxScale. Ear candy is about using MySQL and Galera for geographic replication, and at the Movies uses MySQL to build big data applications.

Beware of MySQL BLOB Corruption in Older Versions
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Does your dataset consist of InnoDB tables with large BLOB data such that the data is stored in external BLOB pages? Was the dataset created in MySQL version 5.1 and below and without using the InnoDB plugin, or with InnoDB plugin but with MySQL version earlier than 5.1.55? If the answer to both the questions are "YES" then it could very well be that you have a hidden corruption lying around in your dataset.

The post Beware of MySQL BLOB Corruption in Older Versions appeared first on ovais.tariq.

InnoDB crash recovery speed in MySQL 5.6
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It has been a while since I have looked at InnoDB crash recovery. A lot has change in the last few years – we have serious crash recovery performance improvements in MySQL 5.5 and MySQL 5.6, we have solid state drives raising as typical high performance IO subsystem and we also have the ability to set much larger log files and often have a much larger InnoDB Buffer Pool to work with.

First let me revisit the challenge with have with InnoDB configuration. For write-intensive workloads it is extremely important to size innodb_log_file_size for good performance, however the longer log file size you have the longer …

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MySQL Non-unique Indexes
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Somebody wanted to know how to find any non-unique indexes in information_schema of the MySQL. The query takes a session variable with the table name and returns the non-unique indexes by column names. It uses a correlated subquery to exclude the table constraints. A similar query lets you find unique indexes in MySQL. Both queries are in this post.

You set the session variable like this:

SET @sv_table_name := 'member_lab';

You can query the indexes result with the following query:

SELECT   s.table_name
,        s.index_name
, …
  [Read more...]
Showing entries 1 to 10 of 33604 10 Older Entries

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