v.21.1Improvements

Better analysis for min/max/count projection with partition key support

Official CH changelog text
Better analysis for min/max/count projection. Now, with enabled allow_experimental_projection_optimization, virtual min/max/count projection can be used together with columns from partition key. #31474 (Amos Bird).
Improved analysis for min/max/count projections allowing their use alongside columns from the partition key when allow_experimental_projection_optimization is enabled.

Why it matters

This feature enhances query optimization by enabling virtual min/max/count projections to be combined with partition key columns. It allows better pruning and filtering during query execution, improving performance for queries involving these aggregations.

How to use it

Enable the feature by setting the system setting allow_experimental_projection_optimization to 1 or true. Once enabled, queries can leverage virtual min/max/count projections together with partition key columns for optimized execution.

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