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Displaying posts with tag: pt-online-schema-change (reset)

Schema changes in MySQL for OpenStack Trove users
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People using OpenStack Trove instances can hit a common issue in the MySQL world: how to perform schema change operations while minimizing the impact on the database server? Let’s explore the options that can allow online schema changes.

Summary

With MySQL 5.5, pt-online-schema-change from Percona Toolkit is your best option for large tables while regular ALTER TABLE statements are only acceptable for small tables. Also beware of metadata locks.

With MySQL 5.6, almost all types of …

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Avoiding MySQL ALTER table downtime
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MySQL table alterations can interrupt production traffic causing bad customer experience or in worst cases, loss of revenue. Not all DBAs, developers, syadmins know MySQL well enough to avoid this pitfall. DBAs usually encounter these kinds of production interruptions when working with upgrade scripts that touch both application and database or if an inexperienced admin/dev engineer perform the schema change without knowing how MySQL operates internally.

Truths
* Direct MySQL ALTER table locks for duration of change (pre-5.6)
* Online DDL in MySQL 5.6 is not always online and may incurr locks
* Even with …


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Syncing MySQL slave table with pt-online-schema-change
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I recently encountered a situation in which after running Percona Toolkit’s pt-table-checksum on a customer system, 95% of the table on the MySQL master was different on the MySQL slave. Although this table was not a critical part of the infrastructure, from time to time, writes to the table from the master would break replication. Additionally, this table has about 6 million rows, and running pt-table-sync would take sometime. Rebuilding the slave from backup of the master would not be an easy option as well since the slave acts as an archive where it has a …

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Looking out for max values in integer-based columns in MySQL
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Yay! My first blog post! As long as at least 1 person finds it useful, I’ve done my job. Recently, one of my long-term clients was noticing that while their INSERTs were succeeding, a particular column counter was not incrementing. A quick investigation determined the column was of type int(11) and they had reached the maximum value of 2147483647. We fixed this by using pt-online-schema-change to change the column to int(10) unsigned, thus allowing values up to …

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How to monitor ALTER TABLE progress in MySQL
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While working on a recent support issue as a Percona Support Engineer,  I got one question from a customer asking how to monitor ALTER TABLE progress. Actually, for MySQL 5.5 and prior versions, it’s quite difficult to ALTER the table in a running production environment especially for large tables (with millions records). Because it will rebuild and lock the table affecting the performance as well as our users. Therefore even if we start ALTER it’s really important to know when it will …

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Online Schema Upgrade in MySQL Galera Cluster using TOI Method
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December 10, 2013 By Severalnines

As a follow-up to the Webinar on Zero Downtime Schema Changes in Galera Cluster, we’ll now walk you through the detailed steps on how to update your schema. The two methods (TOI and RSU) have both their pros and cons, and given parameters like table size, indexes, key_buffer_size, disk speed, etc., it is possible to estimate the time taken for the schema to be upgraded. Also, please note that a schema change is non-transactional so it would not be …

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Integrating pt-online-schema-change with a Scripted Deployment
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Recently, I helped a client that was having issues with deployments causing locking in their production databases.  At a high level, the two key components used in the environment were:

  • Capistrano (scripted deployments) [website]
  • Liquibase (database version control) [website]

At a high level, they currently used a CLI call to Liquibase as a sub-task within a larger deployment task.  The goal of this engagement was to modify that sub-task to run Liquibase in a …

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Schema changes – what’s new in MySQL 5.6?
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Among many of the improvements you can enjoy in MySQL 5.6, there is one that addresses a huge operational problem that most DBAs and System Administrators encounter in their life: schema changes.

While it is usually not a problem for small tables or those in early stages of product life cycle, schema changes become a huge pain once your tables get a significant amount of data. Planning for maintenance is becoming more and more difficult, and your worldwide users want the service to be up and running 24/7, while on the other hand, …

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Percona Toolkit 2.2.3 released; bug fixes include pt-online-schema-change
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Among all of the excellent events going on like YAPCVelocity, and Percona MySQL University, we recently released Percona Toolkit 2.2.3. It’s a small update that includes the following:

  • pt-online-schema-change did not handle the failure of the DROP TRIGGER statements correctly
  • Created …
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pt-online-schema-change and binlog_format
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Statement-based or row-based, or mixed?  We’ve all seen this discussed at length so I’m not trying to rehash tired arguments.  At a high level, the difference is simple:

  1. Statement based replication (SBR) replicates the SQL statements to the slave to be replayed
  2. Row based replication (RBR) replicates the actual rows changed to the slave to be replayed
  3. Mixed mode uses RBR in the event of a non-deterministic statement, otherwise uses SBR

Recently, I worked with a client to optimize their use of pt-online-schema-change and keep replication delay to a …

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Showing entries 1 to 10 of 11 1 Older Entries

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