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MySQL 8.4 Reference Manual  /  ...  /  ndb_redo_log_reader — Check and Print Content of Cluster Redo Log

25.5.22 ndb_redo_log_reader — Check and Print Content of Cluster Redo Log

Reads a redo log file, checking it for errors, printing its contents in a human-readable format, or both. ndb_redo_log_reader is intended for use primarily by NDB Cluster developers and Support personnel in debugging and diagnosing problems.

This utility remains under development, and its syntax and behavior are subject to change in future NDB Cluster releases.

The C++ source files for ndb_redo_log_reader can be found in the directory /storage/ndb/src/kernel/blocks/dblqh/redoLogReader.

Options that can be used with ndb_redo_log_reader are shown in the following table. Additional descriptions follow the table.


ndb_redo_log_reader file_name [options]

file_name is the name of a cluster redo log file. redo log files are located in the numbered directories under the data node's data directory (DataDir); the path under this directory to the redo log files matches the pattern ndb_nodeid_fs/D#/DBLQH/S#.FragLog. nodeid is the data node's node ID. The two instances of # each represent a number (not necessarily the same number); the number following D is in the range 8-39 inclusive; the range of the number following S varies according to the value of the NoOfFragmentLogFiles configuration parameter, whose default value is 16; thus, the default range of the number in the file name is 0-15 inclusive. For more information, see NDB Cluster Data Node File System Directory.

The name of the file to be read may be followed by one or more of the options listed here:

  • -dump

    Command-Line Format -dump

    Print dump info.

  • --file-key, -K

    Command-Line Format --file-key=key

    Supply file decryption key using stdin, tty, or a my.cnf file.

  • --file-key-from-stdin

    Command-Line Format --file-key-from-stdin

    Supply file decryption key using stdin.

  • Command-Line Format -filedescriptors

    -filedescriptors: Print file descriptors only.

  • Command-Line Format --help

    --help: Print usage information.

  • -lap

    Command-Line Format -lap

    Provide lap info, with max GCI started and completed.

  • Command-Line Format -mbyte #
    Type Numeric
    Default Value 0
    Minimum Value 0
    Maximum Value 15

    -mbyte #: Starting megabyte.

    # is an integer in the range 0 to 15, inclusive.

  • Command-Line Format -mbyteheaders

    -mbyteheaders: Show only the first page header of every megabyte in the file.

  • Command-Line Format -noprint

    -noprint: Do not print the contents of the log file.

  • Command-Line Format -nocheck

    -nocheck: Do not check the log file for errors.

  • Command-Line Format -page #
    Type Integer
    Default Value 0
    Minimum Value 0
    Maximum Value 31

    -page #: Start at this page.

    # is an integer in the range 0 to 31, inclusive.

  • Command-Line Format -pageheaders

    -pageheaders: Show page headers only.

  • Command-Line Format -pageindex #
    Type Integer
    Default Value 12
    Minimum Value 12
    Maximum Value 8191

    -pageindex #: Start at this page index.

    # is an integer between 12 and 8191, inclusive.

  • -twiddle

    Command-Line Format -twiddle

    Bit-shifted dump.

Like ndb_print_backup_file and ndb_print_schema_file (and unlike most of the NDB utilities that are intended to be run on a management server host or to connect to a management server) ndb_redo_log_reader must be run on a cluster data node, since it accesses the data node file system directly. Because it does not make use of the management server, this utility can be used when the management server is not running, and even when the cluster has been completely shut down.