How do I check my Cassandra compaction status?
You can also verify this answer by looking at the code: AbstractionCompactionIterable – getCompactionInfo() uses the bytesRead and totalBytes fields from that class. totalBytes is final and is computed in the constructor, by summing getLengthInBytes() from each file that is part of the compaction.
When compaction happens in Cassandra?
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 trigger compaction on Cassandra?
Compactions are triggered when the min_threshold (4 by default) for SSTables in those windows is reached. The most common queries for time series workloads retrieve the last hour/day/month of data. Cassandra can limit SSTables returned to those having the relevant data.
What is leveled compaction?
Leveled compaction creates sstables of a fixed, relatively small size (5MB by default in Cassandra’s implementation), that are grouped into “levels.” Within each level, sstables are guaranteed to be non-overlapping. Each level is ten times as large as the previous.
What is Cassandra consistency level?
The Cassandra consistency level is defined as the minimum number of Cassandra nodes that must acknowledge a read or write operation before the operation can be considered successful. Different consistency levels can be assigned to different Edge keyspaces.
How do you clean Cassandra tombstones?
Procedure
- Monitor the average transaction time to gauge how often to remove tombstones.
- Stop each Cassandra node.
- Edit the following settings in cassandra. yaml that affect tombstone removal and compaction: tombstone_threshold.
- Run reaper and compaction processes.
- Repeat steps for each node.
- Restart each node.
How do I stop compaction?
To reduce or minimize soil compaction:
- Avoid working wet soil. Soil is most susceptible to compaction when it’s saturated and cannot absorb any more water.
- Reduce tillage. Crop residue can intercept raindrops and prevent the soil surface from sealing and compacting.
- Use the right implements.
Can Cassandra be strongly consistent?
Strong consistency can be achieved if W + R > RF, where R – read CL replica count, W – write CL replica count, RF – replication factor. In this scenario, you get a strong consistency since all client reads always fetches the most recent written data.
How is quorum calculated in Cassandra?
Quorum in Cassandra A quorum is strictly related to a parameter called replication factory. The formula used to calculate quorum is: N / 2 + 1, where N is the sum of replication factors in each data center. To illustrate that, some examples: 1 data center, replication factor of 4 -> quorum is 3.
How long do tombstones last in Cassandra?
By default, this is set to 864000, which is equivalent to 10 days.
Is Cassandra good for deletes?
Cassandra’s processes for deleting data are designed to improve performance, and to work with Cassandra’s built-in properties for data distribution and fault-tolerance. 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.
What is compaction in NoSQL?
To make reads faster, each server in a NoSQL system periodically runs a compaction protocol in the background. Compaction merges multiple sstables into a single sstable by merge-sorting the keys.
What are the types of compaction?
The method of compaction is primarily of four types such as kneading, static, dynamic or impact and vibratory compaction.
What is compaction process?
Compaction is a process of increasing soil density and removing air, usually by mechanical means. The size of the individual soil particles does not change, neither is water removed. Purposeful compaction is intended to improve the strength and stiffness of soil.