This change serves the following purposes: 1. use ScanPredicate instead of TCondition for external table, it can reuse old code branch. 2. simplify and delete some useless old code 3. use ColumnValueRange to save predicate
This change serves the following purposes: 1. use ScanPredicate instead of TCondition for external table, it can reuse old code branch. 2. simplify and delete some useless old code 3. use ColumnValueRange to save predicate