Github user jinfengni commented on a diff in the pull request: https://github.com/apache/drill/pull/406#discussion_r55428219 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/ConvertCountToDirectScan.java --- @@ -103,6 +104,10 @@ public void onMatch(RelOptRuleCall call) { return; } + if (proj != null && !ProjectRemoveRule.isTrivial(proj)) { --- End diff -- With the patch, the following query will not use directScan. {code} select count(*) from cp.`tpch/nation.parquet`; {code} {code} 00-00 Screen : rowType = RecordType(BIGINT EXPR$0): rowcount = 1.0, cumulative cost = {75.1 rows, 425.1 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 169 00-01 Project(EXPR$0=[$0]) : rowType = RecordType(BIGINT EXPR$0): rowcount = 1.0, cumulative cost = {75.0 rows, 425.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 168 00-02 StreamAgg(group=[{}], EXPR$0=[COUNT()]) : rowType = RecordType(BIGINT EXPR$0): rowcount = 1.0, cumulative cost = {75.0 rows, 425.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 167 00-03 Project($f0=[0]) : rowType = RecordType(INTEGER $f0): rowcount = 25.0, cumulative cost = {50.0 rows, 125.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 166 00-04 Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=classpath:/tpch/nation.parquet]], selectionRoot=classpath:/tpch/nation.parquet, numFiles=1, usedMetadataFile=false, columns=[]]]) : rowType = RecordType(): rowcount = 25.0, cumulative cost = {25.0 rows, 25.0 cpu, 0.0 io, 0.0 network, 0.0 memory}, id = 165 {code} I debug a bit. Seems Line 115 is fine. But something is worng in the code Line 117 - 123.
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