[GitHub] clintropolis commented on a change in pull request #6951: Add more sketch aggregator support in Druid SQL

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clintropolis commented on a change in pull request #6951: Add more sketch aggregator support in Druid SQL
URL: https://github.com/apache/incubator-druid/pull/6951#discussion_r252040447
 
 

 ##########
 File path: extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/quantiles/sql/DoublesSketchSqlAggregator.java
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.query.aggregation.datasketches.quantiles.sql;
+
+import com.google.common.collect.ImmutableList;
+import org.apache.calcite.rel.core.AggregateCall;
+import org.apache.calcite.rel.core.Project;
+import org.apache.calcite.rex.RexBuilder;
+import org.apache.calcite.rex.RexLiteral;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.sql.SqlAggFunction;
+import org.apache.calcite.sql.SqlFunctionCategory;
+import org.apache.calcite.sql.SqlKind;
+import org.apache.calcite.sql.type.OperandTypes;
+import org.apache.calcite.sql.type.ReturnTypes;
+import org.apache.calcite.sql.type.SqlTypeFamily;
+import org.apache.calcite.sql.type.SqlTypeName;
+import org.apache.druid.java.util.common.StringUtils;
+import org.apache.druid.query.aggregation.AggregatorFactory;
+import org.apache.druid.query.aggregation.datasketches.quantiles.DoublesSketchAggregatorFactory;
+import org.apache.druid.query.aggregation.datasketches.quantiles.DoublesSketchToQuantilePostAggregator;
+import org.apache.druid.query.aggregation.post.FieldAccessPostAggregator;
+import org.apache.druid.segment.VirtualColumn;
+import org.apache.druid.segment.column.ValueType;
+import org.apache.druid.segment.virtual.ExpressionVirtualColumn;
+import org.apache.druid.sql.calcite.aggregation.Aggregation;
+import org.apache.druid.sql.calcite.aggregation.SqlAggregator;
+import org.apache.druid.sql.calcite.expression.DruidExpression;
+import org.apache.druid.sql.calcite.expression.Expressions;
+import org.apache.druid.sql.calcite.planner.PlannerContext;
+import org.apache.druid.sql.calcite.table.RowSignature;
+
+import javax.annotation.Nullable;
+import java.util.ArrayList;
+import java.util.List;
+
+public class DoublesSketchSqlAggregator implements SqlAggregator
+{
+  private static final SqlAggFunction FUNCTION_INSTANCE = new DoublesSketchSqlAggFunction();
+  private static final String NAME = "APPROX_QUANTILE_DS";
+
+  @Override
+  public SqlAggFunction calciteFunction()
+  {
+    return FUNCTION_INSTANCE;
+  }
+
+  @Nullable
+  @Override
+  public Aggregation toDruidAggregation(
+      final PlannerContext plannerContext,
+      final RowSignature rowSignature,
+      final RexBuilder rexBuilder,
+      final String name,
+      final AggregateCall aggregateCall,
+      final Project project,
+      final List<Aggregation> existingAggregations,
+      final boolean finalizeAggregations
+  )
+  {
+    final DruidExpression input = Expressions.toDruidExpression(
+        plannerContext,
+        rowSignature,
+        Expressions.fromFieldAccess(
+            rowSignature,
+            project,
+            aggregateCall.getArgList().get(0)
+        )
+    );
+    if (input == null) {
+      return null;
+    }
+
+    final AggregatorFactory aggregatorFactory;
+    final String histogramName = StringUtils.format("%s:agg", name);
+    final RexNode probabilityArg = Expressions.fromFieldAccess(
+        rowSignature,
+        project,
+        aggregateCall.getArgList().get(1)
+    );
+
+    if (!probabilityArg.isA(SqlKind.LITERAL)) {
+      // Probability must be a literal in order to plan.
+      return null;
+    }
+
+    final float probability = ((Number) RexLiteral.value(probabilityArg)).floatValue();
+    final int k;
+
+    if (aggregateCall.getArgList().size() >= 3) {
+      final RexNode resolutionArg = Expressions.fromFieldAccess(
+          rowSignature,
+          project,
+          aggregateCall.getArgList().get(2)
+      );
+
+      if (!resolutionArg.isA(SqlKind.LITERAL)) {
+        // Resolution must be a literal in order to plan.
+        return null;
+      }
+
+      k = ((Number) RexLiteral.value(resolutionArg)).intValue();
+    } else {
+      k = DoublesSketchAggregatorFactory.DEFAULT_K;
+    }
+
+    // Look for existing matching aggregatorFactory.
+    for (final Aggregation existing : existingAggregations) {
 
 Review comment:
   This code for agg re-use is in a few places now..  I don't this it's the right time to address this yet I'm more commenting as a note to myself, as I was planning to do something with agg factories as a follow up to #6902 which does a similar thing to consolidate re-use of virtual columns

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