Re: [I] Chart is not showing the columns, if dataset has zero records [superset]

["Ujjwaljain16 (via GitHub)" <gi...@apache.org>]

Ujjwaljain16 commented on issue #34196:
URL: https://github.com/apache/superset/issues/34196#issuecomment-5584059161

   I investigated this against both the current codebase and the historical Superset 4.1.2 stack.
   
   I was able to reproduce the relevant setup with a genuinely empty Parquet file that still contains a valid schema, using the 4.1.2-era dependency versions (`SQLAlchemy 1.4.52`, `duckdb-engine 0.9.5`, and period-correct DuckDB). In the tested cases, DuckDB/Superset preserved the column metadata for both zero-row and non-zero-row sources, including through the metadata paths used by Superset.
   
   I also investigated the previously suspected `duckdb-engine` `cursor.description` behavior and could not establish it as the cause of this issue. The behavior we could reproduce occurs at a different SQLAlchemy layer than the raw DBAPI cursor used by Superset's virtual-dataset metadata path.
   
   At this point I don't have enough evidence to propose a safe code fix for #34196.
   
   Could you provide the following so we can reproduce the original case more precisely?
   
   * A minimal/example Parquet file that reproduces the problem, if possible
   * Whether the dataset is a **Physical** or **Virtual** dataset
   * The exact DuckDB and `duckdb-engine` versions installed in the environment
   * The exact chart error/message shown when the columns are reported as missing
   * Whether the columns are visible immediately after creating the dataset, or disappear after a metadata sync/refresh
   * If it is a virtual dataset, the SQL/query used to create it
   
   With those details, we should be able to identify where the column metadata is actually being lost.
   


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