Columns
- You cannot use ALTER FOREIGN TABLE to drop the location or payload column.
- You cannot use ALTER FOREIGN TABLE to change the location column.
- ALTER FOREIGN TABLE enforces the following rules for Parquet foreign columnar tables:
- No row partitioning (column_option cannot specify ROW and update_specification cannot specify ROWFORMAT)
- No subrow partitioning
- No multicolumn partitions
- No autocompression (column_option cannot specify AUTOCOMPRESS)
Refresh Table
Use the REFRESH operation to generate a new version of the manifest file with updated data. Each REFRESH operation produces a new manifest file while maintaining previous versions.
ALTER FOREIGN TABLE table_name REFRESH SNAPSHOT_LOCATION;
A Directory_Listing operation is performed to fetch all the latest files under the LOCATION and a new version of manifest file is generated with latest file paths.