v.25.8Improvement
Add columns_substreams
Addcolumns_substreams.txtfile to Wide part to track all substreams stored in the part. It helps to track dynamic streams in JSON and Dynamic types and so avoid reading sample of these columns to get the list of dynamic streams (for example for columns sizes calculation). Also now all dynamic streams are reflected insystem.parts_columns. #81091 (Pavel Kruglov).
Why it matters
This feature addresses the difficulty of identifying dynamic streams within JSON and Dynamic columns by avoiding the need to read samples of those columns. It also ensures that all dynamic streams are now reflected insystem.parts_columns, facilitating better monitoring and column sizes calculation.How to use it
The feature is integrated automatically; dynamic streams tracking is enabled by the presence of the newcolumns_substreams.txt file in the Wide part. Users benefit from improved tracking and visibility in system.parts_columns without additional configuration.