MisterRaindrop opened a new issue, #2019:
URL: https://github.com/apache/cloudberry/issues/2019

   Part of #2008. Letters (A, B0–B7, C, D, E) are the PRs listed there; this is 
**D**.
   
   ### Scope
   - Fragments from the engine's plan (files, row-group ranges) assigned to 
segments; one large file may be split by row group.
   - A CustomScan (planner hook, design decision D10) that opens a reader per 
fragment and decodes batches into slots.
   - Projection by field id from the table's Iceberg schema (`ProjectionSet`), 
so files written before a column was added or renamed read correctly; only 
needed columns are read.
   - Row-group pruning from the query's quals against Parquet statistics; 
`EXPLAIN ANALYZE` reports row groups skipped.
   - With it: #1989 name mapping for files without field ids.
   
   ### Out of scope
   Delete files (E), time travel (#1683 §2.3), ANALYZE beyond the current 
zero-sample no-op.
   
   ### Depends on
   A, B2, B4. Skeleton, projection and pruning are testable against the stub 
and local files first.
   
   ### Acceptance
   - Same rows as Spark on the same table, including one Spark evolved (column 
added, renamed, dropped, int promoted to long).
   - A file split into three fragments reads the same as whole; every segment 
reads only its fragments.
   - `EXPLAIN ANALYZE` shows pruning for a selective predicate and none for 
`WHERE true`.
   - Unsupported or dictionary-encoded columns are refused naming the column; 
cancel mid-scan releases the reader.
   


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