Minor: Add tests for using FilterExec when parquet was pushed down

datafusion/sqllogictest/test_files/parquet.slt

@@ -202,6 +202,65 @@ SELECT id, CAST(string_col AS varchar) FROM alltypes_plain
 0 0
 1 1
 
+# Query with filtering on a column
+query I
+select id from alltypes_plain where id > 3;
+----
+4
+5
+6
+7
+
+# When filter pushdown is not enabled, ParquetExec only filters based on
+# metadata, so a FilterExec is required to filter the
+# output of the `ParquetExec`
+query TT
+EXPLAIN SELECT id FROM alltypes_plain WHERE id > 3;
+----
+logical_plan
+01)Filter: alltypes_plain.id > Int32(3)
+02)--TableScan: alltypes_plain projection=[id], partial_filters=[alltypes_plain.id > Int32(3)]
+physical_plan
+01)CoalesceBatchesExec: target_batch_size=8192
+02)--FilterExec: id@0 > 3
+03)----RepartitionExec: partitioning=RoundRobinBatch(2), input_partitions=1
+04)------ParquetExec: file_groups={1 group: [[WORKSPACE_ROOT/parquet-testing/data/alltypes_plain.parquet]]}, projection=[id], predicate=id@0 > 3, pruning_predicate=CASE WHEN id_null_count@1 = id_row_count@2 THEN false ELSE id_max@0 > 3 END, required_guarantees=[]
+
+
+# Enable predicate pushdown
+statement ok
+set datafusion.execution.parquet.pushdown_filters = true;
+
+# Query with filtering on a column
+query I
+select id from alltypes_plain where id > 3;
+----
+4
+5
+6
+7
+
+# When filter pushdown *is* enabled, ParquetExec can filter exactly,
+# not just metadata, so we expect to see no FilterExec
+#once https://github.com/apache/datafusion/issues/4028 is fixed
+
+query TT
+EXPLAIN SELECT id FROM alltypes_plain WHERE id > 3;
+----
+logical_plan
+01)Filter: alltypes_plain.id > Int32(3)
+02)--TableScan: alltypes_plain projection=[id], partial_filters=[alltypes_plain.id > Int32(3)]
+physical_plan
+01)CoalesceBatchesExec: target_batch_size=8192
+02)--FilterExec: id@0 > 3
+03)----RepartitionExec: partitioning=RoundRobinBatch(2), input_partitions=1
+04)------ParquetExec: file_groups={1 group: [[WORKSPACE_ROOT/parquet-testing/data/alltypes_plain.parquet]]}, projection=[id], predicate=id@0 > 3, pruning_predicate=CASE WHEN id_null_count@1 = id_row_count@2 THEN false ELSE id_max@0 > 3 END, required_guarantees=[]
+
+# reset pushdown
+statement ok
+set datafusion.execution.parquet.pushdown_filters = false;
+
+
 # Clean up
 statement ok
 DROP TABLE alltypes_plain;