v.21.12New Features

Add Map Combinator and Rename Mapped Arrays in ClickHouse

Official CH changelog text
Add Map combinator for Map type. - Rename old sum-, min-, max- Map for mapped arrays to sum-, min-, max- MappedArrays. #24539 (Ildus Kurbangaliev).
Introduces a new map combinator function for the Map data type in ClickHouse, and renames the existing sum-, min-, and max- combinators for mapped arrays to sum-, min-, and max- MappedArrays respectively.

Why it matters

The feature provides a native combinator to perform aggregation on Map type columns, enabling more straightforward and efficient operations on map-structured data. Renaming the old combinators clarifies their purpose by distinguishing those that operate on mapped arrays from those now introduced for Map types, thus improving usability and reducing ambiguity.

How to use it

Users can apply the new map combinator directly in aggregation queries for Map columns. The old combinators for mapped arrays have been renamed, so users should update their queries to use the new names sum-MappedArrays, min-MappedArrays, and max-MappedArrays when working with mapped arrays.

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