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Category: MySQL Data Recovery

Recover Table Structure From InnoDB Dictionary

When a table gets dropped MySQL removes respective .frm file. This post explain how to recover table structure if the table was dropped. You need the table structure to recover a dropped table from InnoDB tablespace. The B+tree structure of InnoDB index doesn’t contain any information about field types. MySQL needs to know that in […]

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Take image from corrupted hard drive

There are at least two cases when it makes sense to take an image from a corrupted hard drive as soon as possible: disk hardware errors and corrupted filesystem. Faulty hard drives can give just one chance to read a block, so there is no time for experiments. The similar picture with corrupted filesystems. Obviously something […]

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Recover Corrupt MySQL Database

UPDATE: We announced online data recovery from corrupt databases. Check it out on https://recovery.twindb.com/ UPDATE (01/01/2017): We stopped further development of undrop-for-innodb and do not support its open source versions. The unDROP for InnoDB tool can be used to recover corrupt MySQL database. In this post we will show how to repair MySQL database if […]

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Repair Corrupted InnoDB Table with Corruption in Secondary Index

UPDATE: We announced online data recovery from corrupt databases. Check it out on https://recovery.twindb.com/ UPDATE (01/01/2017): We stopped further development of undrop-for-innodb and do not support its open source versions. InnoDB provides no means to repair corrupted table space. Once a table got corrupt the only way to repair MySQL files is to start it […]

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Recover after DROP TABLE, innodb_file_per_table is ON

UPDATE (01/01/2017): We stopped further development of undrop-for-innodb and do not support its open source versions. Introduction In the previous post we described the situation when TwinDB recovery toolkit can be used to recover accidentaly dropped table in the case innodb_file_per_table=OFF setting. In this post we will show how to recover MySQL table or database […]

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Recover after DROP TABLE, innodb_file_per_table is OFF

UPDATE (01/01/2017): We stopped further development of undrop-for-innodb and do not support its open source versions. Introduction Human mistakes are inevitable. Wrong “DROP DATABASE” or “DROP TABLE” may destroy critical data on the MySQL server. Backups would help however they’re not always available. This situation is frightening but not hopeless. In many cases it is […]

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InnoDB dictionary

Why Does InnoDB Need Dictionary InnoDB dictionary is a set of internal tables InnoDB uses to maintain various information about user tables. It serves as API between a human and the database. While the humans refer tables by their names, InnoDB works with integer identifiers. The dictionary stores correspondence between table name and index_id. The […]

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