v.24.7Experimental Feature

Fix Dynamic Subcolumn Reading from Altered Memory Table

Official CH changelog text
Fix reading Dynamic subcolumns from altered Memory table. Previously if max_types parameter of a Dynamic type was changed in Memory table via alter, further subcolumns reading can return wrong result. #66066 (Kruglov Pavel).
Fixes reading Dynamic subcolumns from Memory tables after altering the max_types parameter to prevent incorrect query results.

Why it matters

Previously, when the max_types parameter of a Dynamic type was changed via ALTER on a Memory table, reading subcolumns could return incorrect data. This fix ensures that after altering max_types, subsequent reads of subcolumns reflect the correct structure and data, improving reliability and correctness.

How to use it

Users simply need to upgrade to the ClickHouse version including this fix. After that, altering the max_types parameter on a Dynamic type column in a Memory table using ALTER TABLE will work correctly without any further action.

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