Cassandra Caching Mechanisms (Row Cache, Key Cache, etc.)
Introduction
The caching mechanism is an important component of the distributed database Cassandra, used to improve data access efficiency and reduce queries to the primary table.
Row Cache
The row cache refers to the process of caching entire rows (including all columns) in memory.
- Advantages: Can improve data access speed because data can be read directly from memory without needing to retrieve it from the primary table.
- Disadvantages: Without an appropriate caching strategy, it may lead to excessive cache usage, resulting in disk fragmentation and performance degradation.
Column Cache
The column cache refers to the process of caching a specific column (including all rows) in memory.
- Advantages: Can improve data access speed because data can be read directly from memory without needing to retrieve it from the primary table.
- Disadvantages: Without an appropriate caching strategy, it may lead to excessive cache usage, resulting in disk fragmentation and performance degradation.
Row-Column Composite Cache
The row-column composite cache refers to the process of caching both entire rows and a specific column in memory simultaneously.
- Advantages: Can improve data access speed because data can be read directly from memory without needing to retrieve it from the primary table.
- Disadvantages: Without an appropriate caching strategy, it may lead to excessive cache usage, resulting in disk fragmentation and performance degradation.
Optimizing the Caching Mechanism
Ensuring a reasonable caching strategy is a key step, which can be achieved by setting different cache levels, monitoring cache size, and clearing expired data in a timely manner.
- Ensuring a reasonable caching strategy can help reduce disk access and improve system performance.
Examples
# row_cache
Example of row caching
- Name: row_cache_example
- Value: 200MB
# column_cache
Example of column caching
- Name: column_cache_example
- Value: 100MB
# row_column_composite_cache
Example of row-column composite caching
- Name: row_column_composite_cache_example
- Value: 500MB