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Impacts of max_allowed_packet size problems on your MySQL database

We recently run into some troubles with max_allowed_packet size problems during backups with the FromDual Backup/Recovery Manager and thus I investigated a bit more in the symptoms of such problems.

Read more about: max_allowed_packet.

A general rule for max_allowed_packet size to avoid problems is: All clients and the server should have set the same value for max_allowed_packet size!

I prepared some data for the test which looked as follows:

mysql> SELECT id, LEFT(data, 30), LENGTH(data), ts FROM test; …

Dumping BLOB's from the MySQL database

A customer who is handling digital certificates had a problem with one of those. So we had to investigate.

Because the certificate is in binary form it is stored in a BLOB and we had to extract it from the database to do some verifications.

What first came to my mind was to extract the certificate with the SELECT INTO OUTFILE command. But the verification tool complained and told us that the certificate has a wrong format.

Luckily I found in the documentation the following statement: If you use INTO …

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