drill

cf2b8889 - Join order: Use parquet row count as the basis of scan cost. Transform select count(*)/count(columnName) into DirectGroupScan when possible.

Join order: Use parquet row count as the basis of scan cost. Transform select count(*)/count(columnName) into DirectGroupScan when possible. Nullable return type for extract function. Fix a bug in DrillProjectRule. Fix bug in ProjectPrule, set Direction for RelCollation trait. Set nullable properly for extract function's return type and 'any' type in view DDL or table field lists.