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Displaying posts with tag: Database Repair (reset)

Temporary table naming scheme in 5.6 and before
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Benchmarking is a popular topic. People love drawing graphs as much as watching how X is 10% faster than Y; there must be something special in measurements.

For a DBA, however, more tangible improvements come from less popular area of database maintenance. While MariaDB spreads FUD around InnoDB (nonetheless still uses it) I have to admit InnoDB gets more friendly to DBAs.

In MySQL 5.6 new temporary table naming scheme was introduced – one of …

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Resolving page corruption in compressed InnoDB tables
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Sometimes corruption is not the true corruption. Corruption in compressed InnoDB tables may be a false positive.

Compressed InnoDB table may hit false checksum verification failure. The bug (http://bugs.mysql.com/bug.php?id=73689) reveals itself in the error log as follows:

2014-10-18 08:26:31 7fb114254700 InnoDB: Compressed page type (17855); stored checksum in field1 0; calculated checksums for field1: crc32 4289414559, innodb 0, none 3735928559; page LSN 24332465308430; page number (if stored to page already) 60727; space id (if stored to page already) 448
InnoDB: Page …
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Recover Corrupt MySQL Database
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The unDROP for InnoDB tool can used to recover corrupt MySQL database. In this post we will show how to repair MySQL database if its files became corrupted and even innodb_force_recovery=6 doesn’t help.

The corruption of InnoDB tablespace may be caused by many reasons. A dying hard drive can write garbage, thus page checksum will be wrong. InnoDB then reports to the error log:

InnoDB: Database page corruption on disk or a failed
InnoDB: file read of page 4.

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Repair Corrupted InnoDB Table with Corruption in Secondary Index
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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 with innodb_force_recovery={4,5,6} in hope that you can dump the table, so you can rebuild the table space from scratch. At least this is what the manual says. But let’s take a closer look at InnoDB corruption. In some case you can repair InnoDB table space much faster.

UPDATE: If corruption is in PRIMARY index check post Recover Corrupt MySQL Database

What InnoDB provides to repair tablespace corruption

InnoDB …

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Showing entries 1 to 4

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