Aggregation, Ordering and filtering

Apache CouchDB is a document-oriented NoSQL database that provides flexible data modeling and querying capabilities. Here’s a brief overview of aggregation, ordering, and filtering in CouchDB:

Aggregation: CouchDB provides map-reduce views for data aggregation. Views are defined using JavaScript functions that emit key-value pairs, which can be aggregated and reduced to produce summary results. Aggregation functions can perform operations such as counting, summing, averaging, and grouping data.

Ordering: CouchDB views can be ordered by keys, either ascending or descending. Views can also be paginated to retrieve a specific subset of the results. Ordering is performed using the “startkey”, “endkey”, “descending”, and “limit” query parameters.

Filtering: CouchDB views can be filtered using key ranges, regular expressions, or custom filter functions. Key ranges are defined using the “startkey” and “endkey” query parameters, while regular expressions are defined using the “key” and “value” query parameters. Custom filter functions are defined using JavaScript and can implement arbitrary logic to filter results.

Overall, CouchDB provides a powerful set of tools for aggregating, ordering, and filtering data. These features enable developers to build complex applications with efficient data access and manipulation capabilities.