What is Nodetool compact?

What is Nodetool compact?

Forces a major compaction on one or more tables. cassandra-env.sh. The location of the cassandra-env.sh file depends on the type of installation: Package installations.

What is cassandra compaction?

Cassandra Compaction is a process of reconciling various copies of data spread across distinct SSTables. Cassandra performs compaction of SSTables as a background activity. Cassandra has to maintain fewer SSTables and fewer copies of each data row due to compactions improving its read performance.

How do you run a compaction in Cassandra?

Run nodetool, with the following command: nodetool –host compact By default, host connects to the local Cassandra instance. Run this command against each Cassandra node individually. Important: Only one compaction can be performed at a time.

How do I check my Cassandra compaction status?

If you grep the cassandra log file for lines containing Compacting you will find the sstables that are part of a compaction. If you sum these sizes and multiply by the inverse of your compression ratio for the column family you will get pretty close to the total.

What is Nodetool repair?

Repair – a process that runs in the background and synchronizes the data between nodes. When running nodetool repair on a single node, it acts as the repair master. Only the data contained in the master node and its replications will be repaired.

What does Nodetool scrub do?

Scrub automatically discards broken data and removes any tombstoned rows that have exceeded gc_grace period of the table. If partition key values do not match the column data type, the partition is considered corrupt and the process automatically stops.

How do you avoid tombstones in Cassandra?

How can I avoid tombstone issues?

1. Avoid queries that will run on all partitions in the table (eg queries with no WHERE clause, or any query that requires ALLOW FILTERING).
2. Alter range queries to avoid querying deleted data, or operate on a narrower range of data.

What does Nodetool cleanup do?

Cleans up keyspaces and partition keys no longer belonging to a node.

What does Nodetool rebuild do?

Rebuilds data by streaming from other nodes. This command operates on multiple nodes in a cluster and streams data only from a single source replica when rebuilding a token range. Use this command to add a new datacenter to an existing cluster.

How do I stop compaction in Cassandra?

Procedure

1. Log in to the server where a Cassandra node is installed.
2. Go to /apache-cassandra/bin directory.
3. Type ./nodetool setcompactionthroughput 0. Tip: To run nodetool, JAVA_HOME must be set to the location of IBM JDK 8. Setting the value to 0 , disables compaction throttling.

How are deletes handled in Cassandra?

Cassandra treats a delete as an insert or upsert. The data being added to the partition in the DELETE command is a deletion marker called a tombstone. After this amount of time has ended, Cassandra marks the record with a tombstone, and handles it like other tombstoned records.

When should I run Nodetool cleanup?

You should run nodetool cleanup whenever you scale-out (expand) your cluster, and new nodes are added to the same DC. The scale out process causes the token ring to get re-distributed. As a result, some of the nodes will have replicas for tokens that they are no longer responsible for (taking up disk space).