Spark SQL is a Spark module for structured data processing. It provides a programming abstraction called DataFrames and can also act as a distributed SQL query engine. Elasticsearch Spark integration allows us to read data using SQL queries.
Spark SQL works with structured data; in other words, all entries are expected to have the same structure (the same number of fields, of the same type and name). Using unstructured data (documents with different structures) is not supported and will cause problems.
