NDB_INDEX_STAT(1)

NAME
ndb_index_stat - NDB index statistics utility

SYNOPSIS

ndb_index_stat options

DESCRIPTION

ndb_index_stat provides per-fragment statistical information about indexes on NDB tables. This includes cache version and age, number of index entries per partition, and memory consumption by indexes. Usage.PP To obtain basic index statistics about a given NDB table, invoke ndb_index_stat as shown here, with the name of the table as the first argument and the name of the database containing this table specified immediately following it, using the --database (-d) option:

    ndb_index_stat table -d database

In this example, we use ndb_index_stat to obtain such information about an NDB table named mytable in the test database:

    shell> ndb_index_stat -d test mytable
    table:City index:PRIMARY fragCount:2
    sampleVersion:3 loadTime:1399585986 sampleCount:1994 keyBytes:7976
    query cache: valid:1 sampleCount:1994 totalBytes:27916
    times in ms: save: 7.133 sort: 1.974 sort per sample: 0.000
    NDBT_ProgramExit: 0 - OK

sampleVersion is the version number of the cache from which the statistics data is taken. Running ndb_index_stat with the --update option causes sampleVersion to be incremented.

loadTime shows when the cache was last updated. This is expressed as seconds since the Unix Epoch.

sampleCount is the number of index entries found per partition. You can estimate the total number of entries by multiplying this by the number of fragments (shown as fragCount).

sampleCount can be compared with the cardinality of SHOW INDEX or INFORMATION_SCHEMA.STATISTICS, although the latter two provide a view of the table as a whole, while ndb_index_stat provides a per-fragment average.

keyBytes is the number of bytes used by the index. In this example, the primary key is an integer, which requires four bytes for each index, so keyBytes can be calculated in this case as shown here:

        keyBytes = sampleCount * (4 bytes per index) = 1994 * 4 = 7976

This information can also be obtained using the corresponding column definitions from INFORMATION_SCHEMA.COLUMNS (this requires a MySQL Server and a MySQL client application).

totalBytes is the total memory consumed by all indexes on the table, in bytes.

Timings shown in the preceding examples are specific to each invocation of ndb_index_stat.

The --verbose option provides some additional output, as shown here:

    shell> ndb_index_stat -d test mytable --verbose
    random seed 1337010518
    connected
    loop 1 of 1
    table:mytable index:PRIMARY fragCount:4
    sampleVersion:2 loadTime:1336751773 sampleCount:0 keyBytes:0
    read stats
    query cache created
    query cache: valid:1 sampleCount:0 totalBytes:0
    times in ms: save: 20.766 sort: 0.001
    disconnected
    NDBT_ProgramExit: 0 - OK
    shell>

Options.PP The following table includes options that are specific to the MySQL Cluster ndb_index_stat utility. Additional descriptions are listed following the table. For options common to most MySQL Cluster programs (including ndb_index_stat), see Options Common to MySQL Cluster Programs(1).

Table 18.93. This table describes command-line options for the ndb_index_stat program

ndb_index_stat statistics options. The following options are used to generate index statistics. They work with a given table and database. They cannot be mixed with system options (see ndb_index_stat system options).

    • --database=name, -d name
    Command-Line Format | --database=name
    Permitted Values | Type | string
     | Default | [none]
     | Min Value |
     | Max Value |

    The name of the database that contains the table being queried.

    • --delete
    Command-Line Format | --delete
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Delete the index statistics for the given table, stopping any auto-update that was previously configured.

    • --update
    Command-Line Format | --update
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Update the index statistics for the given table, and restart any auto-update that was previously configured.

    • --dump
    Command-Line Format | --dump
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Dump the contents of the query cache.

    • --query=#
    Command-Line Format | --query=#
    Permitted Values | Type | numeric
     | Default | 0
     | Min Value | 0
     | Max Value | MAX_INT

    Perform random range queries on first key attribute (must be int unsigned).

ndb_index_stat system options. The following options are used to generate and update the statistics tables in the NDB kernel. None of these options can be mixed with statistics options (see ndb_index_stat statistics options).

    • --sys-drop
    Command-Line Format | --sys-drop
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Drop all statistics tables and events in the NDB kernel. This causes all statistics to be lost.

    • --sys-create
    Command-Line Format | --sys-create
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Create all statistics tables and events in the NDB kernel. This works only if none of them exist previously.

    • sys-create-if-not-exist
    Command-Line Format | --sys-create-if-not-exist
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Create any NDB system statistics tables or events (or both) that do not already exist when the program is invoked.

    • --sys-create-if-not-valid
    Command-Line Format | --sys-create-if-not-valid
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Create any NDB system statistics tables or events that do not already exist, after dropping any that are invalid.

    • --sys-check
    Command-Line Format | --sys-check
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Verify that all required system statistics tables and events exist in the NDB kernel.

    • --sys-skip-tables
    Command-Line Format | --sys-skip-tables
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Do not apply any --sys-* options to any statistics tables.

    • --sys-skip-events
    Command-Line Format | --sys-skip-events
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Do not apply any --sys-* options to any events.

    • --verbose
    Command-Line Format | --verbose
    Permitted Values | Type | boolean
     | Default | false
     | Min Value |
     | Max Value |

    Turn on verbose output.

    • --loops=#
    Command-Line Format | --loops=#
    Permitted Values | Type | numeric
     | Default | 0
     | Min Value | 0
     | Max Value | MAX_INT

    Repeat commands this number of times (for use in testing).

COPYRIGHT

Copyright © 1997, 2016, Oracle and/or its affiliates. All rights reserved.

This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.

This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.

SEE ALSO
For more information, please refer to the MySQL Reference Manual, which may already be installed locally and which is also available online at http://dev.mysql.com/doc/.

AUTHOR
Oracle Corporation (http://dev.mysql.com/).