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

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>

If the only output from the program is NDBT_ProgramExit: 0 - OK, this may indicate that no statistics yet exist. To force them to be created (or updated if they already exist), invoke ndb_index_stat with the --update option, or execute ANALYZE TABLE on the table in the mysql client. Options

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

Table 21.34. Command-line options for the ndb_index_stat program
Format | Description | Added, Deprecated, or Removed
--database=name, -d | Name of database containing table | (Supported in all MySQL 5.7 based releases)
--delete | Delete index statistics for table, stopping any auto-update previously configured | (Supported in all MySQL 5.7 based releases)
--update | Update index statistics for table, restarting any auto-update previously configured | (Supported in all MySQL 5.7 based releases)
--dump | Print query cache | (Supported in all MySQL 5.7 based releases)
--query=# | Perform random range queries on first key attr (must be int unsigned) | (Supported in all MySQL 5.7 based releases)
--sys-drop | Drop any statistics tables and events in NDB kernel (all statistics are lost) | (Supported in all MySQL 5.7 based releases)
--sys-create | Create all statistics tables and events in NDB kernel, if none of them already exist | (Supported in all MySQL 5.7 based releases)
--sys-create-if-not-exist | Create any statistics tables and events in NDB kernel that do not already exist | (Supported in all MySQL 5.7 based releases)
--sys-create-if-not-valid | Create any statistics tables or events that do not already exist in the NDB kernel, after dropping any that are invalid | (Supported in all MySQL 5.7 based releases)
--sys-check | Verify that NDB system index statistics and event tables exist | (Supported in all MySQL 5.7 based releases)
--sys-skip-tables | Do not apply sys-* options to tables | (Supported in all MySQL 5.7 based releases)
--sys-skip-events | Do not apply sys-* options to events | (Supported in all MySQL 5.7 based releases)
--verbose, -v | Turn on verbose output | (Supported in all MySQL 5.7 based releases)
--loops=# | Set the number of times to perform given command; default is 0 | (Supported in all MySQL 5.7 based releases)

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
    Type | String
    Default Value | [none]
    Minimum Value |
    Maximum Value |

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

    • --delete
    Command-Line Format | --delete
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum Value |

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

    • --update
    Command-Line Format | --update
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum Value |

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

    • --dump
    Command-Line Format | --dump
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum Value |

    Dump the contents of the query cache.

    • --query=#
    Command-Line Format | --query=#
    Type | Numeric
    Default Value | 0
    Minimum Value | 0
    Maximum 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
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum 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
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum 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
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum 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
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum 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
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum Value |

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

    • --sys-skip-tables
    Command-Line Format | --sys-skip-tables
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum Value |

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

    • --sys-skip-events
    Command-Line Format | --sys-skip-events
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum Value |

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

    • --verbose
    Command-Line Format | --verbose
    Type | Boolean
    Default Value | false
    Minimum Value |
    Maximum Value |

    Turn on verbose output.

    • --loops=#
    Command-Line Format | --loops=#
    Type | Numeric
    Default Value | 0
    Minimum Value | 0
    Maximum Value | MAX_INT

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

COPYRIGHT

Copyright © 1997, 2020, Oracle and/or its affiliates.

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/).