How to know the size of a keyspace and column fami

问题:

Recently I've started working on Grails integration with Cassandra using the Java driver for cassandra(cassandra-driver-core-2.0.2). So I was curious to know how we can find out how much size our table is taking to store the data in cassandra DB.

I have created a keyspace with name Customkeyspace and a column family called Movie in it. So I was curious to know which tool/Command I have to use to know the size of the keyspace/Column family ?

回答1:

To get statistics regarding column families in Cassandra, you can simply run the command:

nodetool cfstats

It reports statistics about tables which include the live data size as well as on disk.

The documentation about this utility for Cassandra 2.1 is available here.

回答2:

To get the statistics regarding column families in Cassandra with respect to keyspaces or tables, you can simply run the below command:

nodetool cfstats

Result: This will return the complete statistics related to available keyspaces.

But, in case you want to find out the statistics of specific keyspaces or tables, run below command:

For Keyspace(s) : nodetool cfstats <keyspace_name> OR nodetool cfstats -H <keyspace_name>

For Table(s) : nodetool tablestats <keyspace_name>.<table_name> OR nodetool tablestats -H <keyspace_name>.<table_name>

Note: -H denotes Human Readable format

For more details please refer, nodetool cfstats

Findings:

1. You might see SSTable count as 0

2. Space used (live) and Space used (total) as 0 bytes

To know WHY(s) of the above two findings please refer: Reason of why SSTable count shown as 0