Addressing MySQL Error 1259 – SQLSTATE: HY000 (ER_ZLIB_Z_DATA_ERROR): A Guide to Resolving ZLIB Input Data Corruption

Encountering MySQL Error 1259 with SQLSTATE HY000, which corresponds to ER_ZLIB_Z_DATA_ERROR, indicates that there is an issue with compressed data within MySQL, specifically pointing to corruption in the ZLIB compressed input data. This error can occur in various scenarios where data compression is involved, such as with table compression, compressed protocol communication, or when using compressed backup files.

Understanding the Error

Error 1259 is an indication that MySQL has encountered corrupted data during an operation involving ZLIB compression. ZLIB is often used within MySQL for compressing data to save space or for network communication efficiency. If the compressed data is corrupted, MySQL cannot properly decompress it, leading to this error.

Common Scenarios and Fixes

Scenario 1: Corrupted Compressed Table

If you are using compressed tables (for example, with InnoDB table compression) and encounter this error, it could be due to issues with the underlying storage or file system corruption.


  • Check and repair the file system to ensure there are no underlying disk issues.
  • Use the MySQL CHECK TABLE command to verify the integrity of the table.
  • If the table is found to be corrupted, use the REPAIR TABLE command if applicable, or restore the table from a backup.

Scenario 2: Issues with Compressed Backup Files

Error 1259 can occur when attempting to restore data from a compressed backup file that has been corrupted.


  • Verify the integrity of the backup file using checksums or hash values.
  • Attempt to decompress the backup file manually using external ZLIB tools to check for corruption.
  • If the backup file is indeed corrupted, you may need to obtain a new copy or restore from a different backup.

Scenario 3: Compressed Client/Server Communication

MySQL supports compressed client/server protocol, which can lead to Error 1259 if there’s data corruption during transmission.


  • Ensure that the network connection is stable and reliable.
  • Disable the compressed protocol to check if the error persists without compression.
  • Investigate any potential issues with the client or server that might be causing data corruption.

Sample Code to Demonstrate Fixes

Here’s an example of how you might use the CHECK TABLE and REPAIR TABLE commands:

-- Check the integrity of the table
CHECK TABLE your_compressed_table;

-- If corruption is reported, attempt to repair it
REPAIR TABLE your_compressed_table;

And for working with backup files:

# Verify the integrity of the backup file
md5sum your_backup_file.sql.gz

# Manually decompress the file to check for errors
gunzip -t your_backup_file.sql.gz

Professional Tips

  • Regularly verify the integrity of your backups using checksums or hashes to avoid unpleasant surprises during restoration.
  • Keep your MySQL server and client libraries updated to the latest stable versions to benefit from any bug fixes related to compression.
  • Consider using file system-level compression instead of table-level compression for more flexibility and potentially easier troubleshooting.

If you are frequently encountering this error, it may be worth reviewing your data handling processes to ensure that compression and decompression operations are being performed correctly and that your storage systems are reliable.

By understanding the contexts in which Error 1259 occurs and following these troubleshooting steps, you should be able to diagnose and rectify the issue of ZLIB input data corruption within MySQL. Remember to always maintain regular backups and verify their integrity to minimize the risk of data loss.

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