v.25.8Improvement

Fix iceberg reading by field ids

Fix iceberg reading by field ids for complex types. #84821 (Konstantin Vedernikov).
Fixed reading of Iceberg data by field IDs for complex data types in ClickHouse.

Why it matters

This fix addresses issues in reading Iceberg table data where complex types (such as arrays, structs, and maps) are involved. By correctly using field IDs, ClickHouse can accurately interpret and read complex nested data structures, improving compatibility and correctness when querying Iceberg tables.

How to use it

Users benefit from this fix automatically when reading data from Iceberg tables with complex types. No additional configuration is required; simply query Iceberg tables as usual, and the improved field ID handling will ensure accurate data retrieval.