src/doc/4.1/_sources/tools/sstable/sstablelevelreset.rst.txt

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sstablelevelreset
-----------------

If LeveledCompactionStrategy is set, this script can be used to reset level to 0 on a given set of sstables. This is useful if you want to, for example, change the minimum sstable size, and therefore restart the compaction process using this new configuration.

See http://cassandra.apache.org/doc/latest/operating/compaction.html#leveled-compaction-strategy for information on how levels are used in this compaction strategy.

Cassandra must be stopped before this tool is executed, or unexpected results will occur. Note: the script does not verify that Cassandra is stopped.

ref: https://issues.apache.org/jira/browse/CASSANDRA-5271

Usage
^^^^^

sstablelevelreset --really-reset <keyspace> <table>

The really-reset flag is required, to ensure this intrusive command is not run accidentally.

Table not found
^^^^^^^^^^^^^^^

If the keyspace and/or table is not in the schema (e.g., if you misspelled the table name), the script will return an error.

Example:: 

    ColumnFamily not found: keyspace/evenlog.

Table has no sstables
^^^^^^^^^^^^^^^^^^^^^

Example::

    Found no sstables, did you give the correct keyspace/table?


Table already at level 0
^^^^^^^^^^^^^^^^^^^^^^^^

The script will not set the level if it is already set to 0.

Example::

    Skipped /var/lib/cassandra/data/keyspace/eventlog-65c429e08c5a11e8939edf4f403979ef/mc-1-big-Data.db since it is already on level 0

Table levels reduced to 0
^^^^^^^^^^^^^^^^^^^^^^^^^

If the level is not already 0, then this will reset it to 0.

Example::

    sstablemetadata /var/lib/cassandra/data/keyspace/eventlog-6365332094dd11e88f324f9c503e4753/mc-8-big-Data.db | grep -i level
    SSTable Level: 1

    sstablelevelreset --really-reset keyspace eventlog
    Changing level from 1 to 0 on /var/lib/cassandra/data/keyspace/eventlog-6365332094dd11e88f324f9c503e4753/mc-8-big-Data.db

    sstablemetadata /var/lib/cassandra/data/keyspace/eventlog-6365332094dd11e88f324f9c503e4753/mc-8-big-Data.db | grep -i level
    SSTable Level: 0