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Category: MySQL Data Recovery

TwinDB Talks On Percona Live 2016

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Percona Live is Christmas in the MySQL world. Naturally, it’s the time when friends and family come together. Everyone is talking about achievements of the year and making New Year’s resolutions. TwinDB at Percona This year, TwinDB does two talks. One about data recovery and the other about backups. The first one will be a […]

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Data Loss After MySQL Restart

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Not so long ago, I had a customer who experienced data loss after a MySQL restart. It was really puzzling. MySQL was up & running for many months, but after the customer restarted the MySQL server all tables have gone. The tables were still visible in the SHOW TABLES output, but they were not readable:

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Recover Corrupted Or Crashed MySQL Database Online

Earlier, we blogged about ways to recover corrupt MySQL database with the TwinDB Data Recovery Toolkit. However, the learning curve of the toolkit is rather steep. It takes time to get familiar with the InnoDB internals and the tool itself. And let’s be honest, nobody’s ever prepared for data loss – people who prepare for disaster […]

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How to Recover Table Structure From FRM Files Online

Recently we announced MySQL Data Recovery Portal. Here, we automated some data recovery routines and published a matching web interface. At first, it was a tool to estimate recovery chances from corrupted InnoDB tablespaces. Now, it’s an even more exciting and useful feature – recovery table structure from FRM files online. There are several methods to recover […]

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How To Evaluate If MySQL Table Can Be Recovered

What Are the Odds a MySQL Table Can Be Recovered? This is the most asked question. Every single customer asks if their MySQL table can be recovered. Although it’s not possible to answer it with 100% confidence, there are ways to estimate recovery chances. I will describe a few tricks. Generally speaking, if data is […]

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How to Handle Wrong Page Type In External Pages

Mainly, the first step to successful MySQL data recovery is finding InnoDB pages with your data. Let’s call it the first step, because prerequisite steps are already done. An InnoDB page type is a two bytes integer in the header of a page. For MySQL data recovery two of them are important: FIL_PAGE_INDEX. Pages of […]

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Presenting TwinDB Data Recovery Toolkit at the #SFMySQL Meetup

On 5 November, I’ll be speaking about Data Recovery Software for MySQL at the #SFMySQL Meetup. You might want to add Slipped & DROP’d your TABLE? Recover w/TwinDB’s Undrop for InnoDB toolkit to your calendar. There will be a demo, and if you want to try to undrop a table yourself bring in a Linux laptop. Further […]

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Resolving Page Corruption In Compressed InnoDB Tables

Sometimes corruption is not what is seems. Corruption in compressed InnoDB tables may be a false positive. Compressed InnoDB tables may hit a false checksum verification failure. The bug (http://bugs.mysql.com/bug.php?id=73689) reveals itself in the error log as follows:

InnoDB complains about a stored checksum being a zero. If you look closely, you’ll find it […]

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Resolving ERROR 1050 42S01 At Line 1 Table Already Exists

When ALTER TABLE crashes the MySQL server, it leaves orphaned records in the InnoDB dictionary. It is annoying because next time you run the same ALTER TABLE query, it will fail with error:

This post explains why it happens and how to fix it. When you run ALTER table, InnoDB follows the plan: Block […]

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