Planet MySQL Planet MySQL: Meta Deutsch Español Français Italiano 日本語 Русский Português 中文
Showing entries 1 to 4

Displaying posts with tag: pt-table-checksum (reset)

How to avoid hash collisions when using MySQL’s CRC32 function
+0 Vote Up -0Vote Down

Percona Toolkit’s  pt-table-checksum performs an online replication consistency check by executing checksum queries on the master, which produces different results on replicas that are inconsistent with the master – and the tool pt-table-sync synchronizes data efficiently between MySQL tables.

The tools by default use the CRC32. Other good choices include MD5 and SHA1. If you have installed the FNV_64 user-defined function, pt-table-sync will detect it and prefer to use it, because it is much faster than the built-ins. You can also use

  [Read more...]
Syncing MySQL slave table with pt-online-schema-change
+0 Vote Up -0Vote Down

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 lot more data than the master.

So how did we solve it? With pt-online-schema-change and a NOOP

  [Read more...]
Check for MySQL slave lag with Percona Toolkit plugin for Tungsten Replicator
+0 Vote Up -0Vote Down

A while back, I made some changes to the plugin interface for pt-online-schema-change which allows custom replication checks to be written. As I was adding this functionality, I also added the --plugin option to pt-table-checksum. This was released in Percona Toolkit 2.2.8.

With these additions, I spent some time writing a plugin that allows Percona Toolkit tools to use Tungsten Replicator to check for slave lag, you can find the code at

  [Read more...]
Taxonomy of database tools
+1 Vote Up -0Vote Down

Taxonomy of Database Tools

In the MySQL ecosphere there is an ecosystem of tools.  Like real-world ecosystems, the “creatures” in the MySQL tools ecosystem can be classified and organized by a taxonomy.  There are already multiple taxonomies of software bugs (e.g. A Taxonomy of Bugs), but as far as I know this is the first Taxonomy of Database Tools.  A taxonomy of database tools serves useful purposes, as discussed in the previously linked page.  For me, the most useful purpose is the high-level ecosystem view which I


  [Read more...]
Showing entries 1 to 4

Planet MySQL © 1995, 2014, Oracle Corporation and/or its affiliates   Legal Policies | Your Privacy Rights | Terms of Use

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.