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  1. MariaDB Server
  2. MDEV-29453

blob data corrupted by INSERT INTO




      After creating a sql dump of my drupal database with mysqldump and then importing it into a fresh mariadb installation, I noticed that for two rows the longblob data got corrupted to all binary zeros (but correct length).

      To make it easier to debug I simplified it to the attached debug.sql file.

      After importing it with

      cat debug.sql | mysql

      for mariadb 10.7.5, 10.8.4 and 10.9.2 the following rows get corrupted:

      name = debug12637_______
      value = 0x00000000...
      name = debug7498___________________
      value = 0x00000000...

      with 10.6.8 it is working correctly:

      name = debug12637_______
      value =  0x78787878...
      name = debug7498___________________
      value =  0x78787878...

      There is no crash, no error log, no nothing... I was lucky that one of my users noticed the corruption after a few hours.

      It must be related to the length of the line or the rows, or something like that, because when I create the dump with "--net-buffer-length 500000" the data is imported correctly.

      update 12/2022:

      • bug is also present in 10.9.4 and 10.10.2
      • bug is present in the official dockerhub mariadb (based on ubuntu) images, as well as with windows binaries - thus seems to be a generic issue (docker images and windows binaries have been tested on two completely different systems)
      • testing different mysql client options (--net-buffer-length 500000 --max-allowed-packet=500000 --unbuffered --show-warnings --compress --binary-mode) did not show any difference
      • setting max-allowed-packet=1G on server-side also does not fix the issue
      • bug seems to be related to these statements in the sql file generated by mysqldump:

        /*!40014 SET UNIQUE_CHECKS=0 */;
        /*!40014 SET FOREIGN_KEY_CHECKS=0 */;
        /*!40000 ALTER TABLE `variable` DISABLE KEYS */;

        but I do not know why

      • creating the dump file with "mysqldump --hex-blob" makes the bug trigger for different rows - maybe due to different encoding length?
      • at this point I do not know how to continue debugging - any help is greatly appreciated


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              thiru Thirunarayanan Balathandayuthapani
              Roosz Michael Roosz
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