How does Cassandra’s indexing work?

Cassandra stores data using a hash-based distributed hash table and utilizes indexes to quickly locate data. The way Cassandra’s indexes work is as follows:

1. Cassandra supports secondary indexes, which allow users to create indexes on non-primary key columns in a table. When an index is created on a non-primary key column, Cassandra stores the index key values and corresponding partition key in an auxiliary index table, and uses this index to quickly retrieve data.
2. Indexing search: When using an index to search, Cassandra first uses the index to locate the corresponding partition key, and then searches for the corresponding data within that partition. This helps reduce the cost of full table scans and improve query efficiency.
3. Index maintenance: Cassandra automatically maintains indexes to ensure data consistency when data is inserted, updated, or deleted. This means there might be additional overhead during write operations, but it guarantees the accuracy and reliability of data when queried.

In general, Cassandra’s indexing works by maintaining secondary indexes to quickly search for data, while also ensuring data consistency and reliability. By using indexes correctly, query efficiency can be increased and performance optimized.