Important

You are viewing the documentation of an older version of the TiDB database (TiDB v5.4).

It is recommended that you use the latest LTS version of the TiDB database.

TiFlash Command-Line Flags

This document introduces the command-line flags that you can use when you launch TiFlash.

server --config-file

  • Specifies the path of the TiFlash configuration file
  • Default: ""
  • You must specify the configuration file. For detailed configuration items, refer to TiFlash configuration parameters.

dttool migrate

  • Migrates the file format of DTFile (for testing or downgrading). Data is migrated in the unit of a single DTFile. If you want to migrate the whole table, you need to locate all the paths similar to <data dir>/t_<table id>/stable/dmf_<file id> and migrate them one by one. You can use scripts to automate the migration.

  • User scenarios:

    • If you need to downgrade TiFlash from a version >= v5.4.0 that has enabled data validation to a version < v5.4.0, you can use this tool to downgrade the data format of the DTFile.
    • If you upgrade TiFlash to a version >= v5.4.0, and if you hope to enable data validation for existing data, you can use this tool to upgrade the data format of the DTFile.
    • Test the space usage and read speed of the DTFile in different configurations.
  • Parameters:

    • --imitative: When you do not use the encryption feature of the DTFile, you can use this flag to avoid using the configuration file and connecting to PD.
    • --version: The version of DTFile. The value options are 1 and 2 (default). 1 is the old version, and 2 is the version corresponding to the new checksum.
    • --algorithm: The hash algorithm used for data validation. The value options are xxh3 (default), city128, crc32, crc64, and none. This parameter is effective only when version is 2.
    • --frame: The size of the validation frame. The default value is 1048576. This parameter is effective only when version is 2.
    • --compression: The target compression algorithm. The value options are lz4 (default), lz4hc, zstd, and none.
    • --level: The target compression level. The default value is -1, which means automatic mode. The value range varies with different compression algorithms.
    • --config-file: The configuration file of dttool migrate is the same as the configuration file of server. When you use the configuration file, exit the local TiFlash server instance. For more information, see --imitative.
    • --file-id: The ID of the DTFile. For example, the ID of the DTFile dmf_123 is 123.
    • --workdir: The parent directory of dmf_xxx.
    • --dry: The dry run mode. Only the migration process is output.
    • --nokeep: Does not keep the original data. When this option is not enabled, dmf_xxx.old files are created.
Warning

TiFlash can read DTFile that uses custom compression algorithms and compression levels. However, only the lz4 algorithm with the default compression level is officially supported. Custom compression parameters have not been thoroughly tested and are only experimental.

Note

For security reasons, DTTool attempts to add a lock to the working directory in the migration mode. Therefore, in the same directory, only one DTTool can perform the migration task at the same time. If you forcibly stop DTTool where the lock is not released, then when you try to rerun DTTool later, it might refuse to perform the migration task.

If you encounter this situation, and if you are aware that removing the LOCK file does not cause any data corruption, you can manually delete the LOCK file in the working directory to release the lock.

dttool bench

  • Provides a basic I/O speed test for the DTFile.

  • Parameters:

    • --version: The version of DTFile. See --version in dttool migrate.
    • --algorithm: The hash algorithm used for data validation. See --algorithm in dttool migrate.
    • --frame: The size of the validation frame. See --frame in dttool migrate.
    • --column: The columns of the table to be tested. The default value is 100.
    • --size: The rows of the table to be tested. The default value is 1000.
    • --field: The field length limit of the table to be tested. The default value is 1024.
    • --random: The random seed. If you do not specify this parameter, the random seed is drawn from the system entropy pool.
    • --encryption: Enables the encryption feature.
    • --repeat: The number of times to repeat the test. The default value is 5.
    • --workdir: The temporary data directory, which points to a path in the file system to be tested. The default value is /tmp/test.

dttool inspect

  • Checks the integrity of the DTFile. Data validation is performed in the unit of a single DTFile. If you want to validate the whole table, you need to locate all the paths similar to <data dir>/t_<table id>/stable/dmf_<file id> and validate them one by one. You can use scripts to automate the validation.

  • User scenarios:

    • After you perform a format upgrade or downgrade, you can validate the data integrity of the DTFile.
    • After you migrate the DTFile to a new environment, you can validate the data integrity of the DTFile.
  • Parameters:

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