Data ingestion and processing – data from one or more transactional data stores, files, real-time streams, or other sources is loaded into a data lake or a relational data warehouse. The load operation usually involves an extract, transform, and load (ETL) or extract, load, and transform (ELT) process in which the data is cleaned, filtered, and restructured for analysis. In ETL processes, the data is transformed before being loaded into an analytical store, while in an ELT process the data is copied to the store and then transformed. Either way, the resulting data structure is optimized for analytical queries. The data processing is often performed by distributed systems that can process high volumes of data in parallel using multi-node clusters. Data ingestion includes both batch processing of static data and real-time processing of streaming data.