Github user jinfengni commented on a diff in the pull request:
https://github.com/apache/drill/pull/882#discussion_r131445381
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/ConvertCountToDirectScan.java
---
@@ -85,109 +91,231 @@ protected ConvertCountToDirectScan(RelOptRuleOperand
rule, String id) {
@Override
public void onMatch(RelOptRuleCall call) {
final DrillAggregateRel agg = (DrillAggregateRel) call.rel(0);
- final DrillScanRel scan = (DrillScanRel) call.rel(call.rels.length -1);
- final DrillProjectRel proj = call.rels.length == 3 ? (DrillProjectRel)
call.rel(1) : null;
+ final DrillScanRel scan = (DrillScanRel) call.rel(call.rels.length -
1);
+ final DrillProjectRel project = call.rels.length == 3 ?
(DrillProjectRel) call.rel(1) : null;
final GroupScan oldGrpScan = scan.getGroupScan();
final PlannerSettings settings =
PrelUtil.getPlannerSettings(call.getPlanner());
- // Only apply the rule when :
+ // Only apply the rule when:
// 1) scan knows the exact row count in getSize() call,
// 2) No GroupBY key,
- // 3) only one agg function (Check if it's count(*) below).
- // 4) No distinct agg call.
+ // 3) No distinct agg call.
if
(!(oldGrpScan.getScanStats(settings).getGroupScanProperty().hasExactRowCount()
&& agg.getGroupCount() == 0
- && agg.getAggCallList().size() == 1
&& !agg.containsDistinctCall())) {
return;
}
- AggregateCall aggCall = agg.getAggCallList().get(0);
-
- if (aggCall.getAggregation().getName().equals("COUNT") ) {
-
- long cnt = 0;
- // count(*) == > empty arg ==> rowCount
- // count(Not-null-input) ==> rowCount
- if (aggCall.getArgList().isEmpty() ||
- (aggCall.getArgList().size() == 1 &&
- !
agg.getInput().getRowType().getFieldList().get(aggCall.getArgList().get(0).intValue()).getType().isNullable()))
{
- cnt = (long) oldGrpScan.getScanStats(settings).getRecordCount();
- } else if (aggCall.getArgList().size() == 1) {
- // count(columnName) ==> Agg ( Scan )) ==> columnValueCount
- int index = aggCall.getArgList().get(0);
-
- if (proj != null) {
- // project in the middle of Agg and Scan : Only when input of
AggCall is a RexInputRef in Project, we find the index of Scan's field.
- // For instance,
- // Agg - count($0)
- // \
- // Proj - Exp={$1}
- // \
- // Scan (col1, col2).
- // return count of "col2" in Scan's metadata, if found.
-
- if (proj.getProjects().get(index) instanceof RexInputRef) {
- index = ((RexInputRef)
proj.getProjects().get(index)).getIndex();
- } else {
- return; // do not apply for all other cases.
- }
- }
+ final CountsCollector countsCollector = new CountsCollector(settings);
+ // if counts were not collected, rule won't be applied
+ if (!countsCollector.collect(agg, scan, project)) {
+ return;
+ }
- String columnName =
scan.getRowType().getFieldNames().get(index).toLowerCase();
+ final RelDataType scanRowType = constructDataType(agg);
- cnt =
oldGrpScan.getColumnValueCount(SchemaPath.getSimplePath(columnName));
- if (cnt == GroupScan.NO_COLUMN_STATS) {
- // if column stats are not available don't apply this rule
- return;
- }
- } else {
- return; // do nothing.
- }
+ final DynamicPojoRecordReader<Long> reader = new
DynamicPojoRecordReader<>(
+ buildSchema(scanRowType.getFieldNames()),
+ Collections.singletonList(countsCollector.getCounts()));
- RelDataType scanRowType =
getCountDirectScanRowType(agg.getCluster().getTypeFactory());
+ final ScanStats scanStats = new
ScanStats(ScanStats.GroupScanProperty.EXACT_ROW_COUNT, 1, 1,
scanRowType.getFieldCount());
+ final GroupScan directScan = new MetadataDirectGroupScan(reader,
oldGrpScan.getFiles(), scanStats);
- final ScanPrel newScan = ScanPrel.create(scan,
-
scan.getTraitSet().plus(Prel.DRILL_PHYSICAL).plus(DrillDistributionTrait.SINGLETON),
getCountDirectScan(cnt),
- scanRowType);
+ final ScanPrel newScan = ScanPrel.create(scan,
+
scan.getTraitSet().plus(Prel.DRILL_PHYSICAL).plus(DrillDistributionTrait.SINGLETON),
directScan,
+ scanRowType);
- List<RexNode> exprs = Lists.newArrayList();
- exprs.add(RexInputRef.of(0, scanRowType));
+ final ProjectPrel newProject = new ProjectPrel(agg.getCluster(),
agg.getTraitSet().plus(Prel.DRILL_PHYSICAL)
+ .plus(DrillDistributionTrait.SINGLETON), newScan,
prepareFieldExpressions(scanRowType), agg.getRowType());
- final ProjectPrel newProj = new ProjectPrel(agg.getCluster(),
agg.getTraitSet().plus(Prel.DRILL_PHYSICAL)
- .plus(DrillDistributionTrait.SINGLETON), newScan, exprs,
agg.getRowType());
+ call.transformTo(newProject);
+ }
- call.transformTo(newProj);
+ /**
+ * For each aggregate call creates field with "count$" prefix and bigint
type.
+ * Constructs record type for created fields.
+ *
+ * @param aggregateRel aggregate relation expression
+ * @return record type
+ */
+ private RelDataType constructDataType(DrillAggregateRel aggregateRel) {
+ List<RelDataTypeField> fields = new ArrayList<>();
+ for (int i = 0; i < aggregateRel.getAggCallList().size(); i++) {
+ RelDataTypeField field = new RelDataTypeFieldImpl("count$" + i, i,
aggregateRel.getCluster().getTypeFactory().createSqlType(SqlTypeName.BIGINT));
--- End diff --
The fieldname in RelDataTypeField "count$0", "count$1" is not very
informative. I think we could either get the field name from the aggregator
operator, or use "count$colname" to indicate what column's count it represents.
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