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MySQL 5.7 Reference Manual  /  ...  /  ndb_redo_log_reader — Check and Print Content of Cluster Redo Log

21.4.22 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.

Note

Prior to NDB 7.2, this utility was named ndbd_redo_log_reader.

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

The following table includes options that are specific to the NDB Cluster program ndb_redo_log_reader. Additional descriptions follow the table. For options common to most NDB Cluster programs (including ndb_redo_log_reader), see Section 21.4.30, “Options Common to NDB Cluster Programs — Options Common to NDB Cluster Programs”.

Table 21.100 This table describes command-line options for the ndb_redo_log_reader program

Format Description Added or Removed

-dump

Print dump info

All MySQL 5.7 based releases

-filedescriptors

Print file descriptors only

All MySQL 5.7 based releases

--help

Print usage information

All MySQL 5.7 based releases

-lap

Provide lap info, with max GCI started and completed

All MySQL 5.7 based releases

-mbyte #

Starting megabyte

All MySQL 5.7 based releases

-mbyteheaders

Show only the first page header of every megabyte in the file

All MySQL 5.7 based releases

-nocheck

Do not check records for errors

All MySQL 5.7 based releases

-noprint

Do not print records

All MySQL 5.7 based releases

-page #

Start with this page

All MySQL 5.7 based releases

-pageheaders

Show page headers only

All MySQL 5.7 based releases

-pageindex #

Start with this page index

All MySQL 5.7 based releases

-twiddle

Bit-shifted dump

All MySQL 5.7 based releases


Usage

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 Files.

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
    Permitted ValuesTypeboolean
    DefaultFALSE

    Print dump info.

  • Command-Line Format-filedescriptors
    Permitted ValuesTypeboolean
    DefaultFALSE

    -filedescriptors: Print file descriptors only.

  • Command-Line Format--help

    --help: Print usage information.

  • -lap

    Command-Line Format-lap
    Permitted ValuesTypeboolean
    DefaultFALSE

    Provide lap info, with max GCI started and completed.

  • Command-Line Format-mbyte #
    Permitted ValuesTypenumeric
    Default0
    Min Value0
    Max Value15

    -mbyte #: Starting megabyte.

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

  • Command-Line Format-mbyteheaders
    Permitted ValuesTypeboolean
    DefaultFALSE

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

  • Command-Line Format-noprint
    Permitted ValuesTypeboolean
    DefaultFALSE

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

  • Command-Line Format-nocheck
    Permitted ValuesTypeboolean
    DefaultFALSE

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

  • Command-Line Format-page #
    Permitted ValuesTypeinteger
    Default0
    Min Value0
    Max Value31

    -page #: Start at this page.

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

  • Command-Line Format-pageheaders
    Permitted ValuesTypeboolean
    DefaultFALSE

    -pageheaders: Show page headers only.

  • Command-Line Format-pageindex #
    Permitted ValuesTypeinteger
    Default12
    Min Value12
    Max Value8191

    -pageindex #: Start at this page index.

    # is an integer between 12 and 8191, inclusive.

  • -twiddle

    Command-Line Format-twiddle
    Permitted ValuesTypeboolean
    DefaultFALSE

    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.


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