v.21.2New Features
Nested Data Type Enhancements with Support for Arbitrary Levels of Nesting and Subcolumns
Data typeNestednow supports arbitrary levels of nesting. Introduced subcolumns of complex types, such assize0inArray,nullinNullable, names ofTupleelements, which can be read without reading of whole column. #17310 (Anton Popov).
Why it matters
This feature allows users to access and read specific subcolumns likesize0 in Array, null in Nullable, and named elements of Tuple directly without reading the entire complex column. It improves query efficiency and flexibility when working with deeply nested or complex data structures.How to use it
Users can leverage this feature by querying subcolumns of complex nested data types directly in their SQL statements, for example, selectingNestedColumn.size0 from an Array or accessing named elements of a Tuple. No special configuration is required; simply reference subcolumns as needed in queries.