Cassandra Design Patterns - Second Edition by Rajanarayanan Thottuvaikkatumana

Author:Rajanarayanan Thottuvaikkatumana [Thottuvaikkatumana, Rajanarayanan]
Language: eng
Format: azw3
Publisher: Packt Publishing
Published: 2015-11-04T05:00:00+00:00

Tip

Wherever the consistency level settings given in this chapter are more than ONE, it is important to make sure that the number of alive nodes in the cluster is greater than or equal to the consistency level setting. For example, if you have a single node Cassandra setup and if you are trying the CQL scripts given in this chapter where there is a consistency level setting THREE, the CQL commands will fail.

Write-heavy pattern

In an IoT application with Cassandra as the data store, if the inflow of the data is very high, the write consistency levels should not be set high. Consistency levels of ANY, LOCAL_ONE, and ONE are ideal. The data comes in with a high velocity, and the data store should work like a sink. In this situation, if the consistency levels are set high, then for each write, the clients have to wait until the write is completed successfully on the required number of nodes as per the consistency level setting. The complexity increases when there are Cassandra clusters spread across multiple data centers in a network operations perspective. When the clients wait for the write to complete because of high consistency level settings, the availability will be lesser, and the efficiency to complete the writes will also become lesser. This, in turn, increases the latency, and the overall application performance will be affected. It is also ideal to avoid secondary indexes in the Cassandra column families where a huge number of writes are taking place.

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