Add statistical type aggregate functions, including autocorrelation, skewness, and linear regression

integration-test/src/main/java/org/apache/iotdb/itbase/constant/BuiltinAggregationFunctionEnum.java

@@ -42,7 +42,14 @@ public enum BuiltinAggregationFunctionEnum {
   AVG("avg"),
   SUM("sum"),
   MAX_BY("max_by"),
-  MIN_BY("min_by");
+  MIN_BY("min_by"),
+  CORR("corr"),
+  COVAR_POP("covar_pop"),
+  COVAR_SAMP("covar_samp"),
+  REGR_SLOPE("regr_slope"),
+  REGR_INTERCEPT("regr_intercept"),
+  SKEWNESS("skewness"),
+  KURTOSIS("kurtosis");
 
   private final String functionName;
 

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/aggregation/AccumulatorFactory.java

@@ -69,6 +69,11 @@ public static boolean isMultiInputAggregation(TAggregationType aggregationType)
     switch (aggregationType) {
       case MAX_BY:
       case MIN_BY:
+      case CORR:
+      case COVAR_POP:
+      case COVAR_SAMP:
+      case REGR_SLOPE:
+      case REGR_INTERCEPT:
         return true;
       default:
         return false;
@@ -84,6 +89,31 @@ public static Accumulator createBuiltinMultiInputAccumulator(
       case MIN_BY:
         checkState(inputDataTypes.size() == 2, "Wrong inputDataTypes size.");
         return new MinByAccumulator(inputDataTypes.get(0), inputDataTypes.get(1));
+      case CORR:
+        checkState(inputDataTypes.size() == 2, "Wrong inputDataTypes size.");
+        return new CorrelationAccumulator(
+            new TSDataType[] {inputDataTypes.get(0), inputDataTypes.get(1)},
+            CorrelationAccumulator.CorrelationType.CORR);
+      case COVAR_POP:
+        checkState(inputDataTypes.size() == 2, "Wrong inputDataTypes size.");
+        return new CorrelationAccumulator(
+            new TSDataType[] {inputDataTypes.get(0), inputDataTypes.get(1)},
+            CorrelationAccumulator.CorrelationType.COVAR_POP);
+      case COVAR_SAMP:
+        checkState(inputDataTypes.size() == 2, "Wrong inputDataTypes size.");
+        return new CorrelationAccumulator(
+            new TSDataType[] {inputDataTypes.get(0), inputDataTypes.get(1)},
+            CorrelationAccumulator.CorrelationType.COVAR_SAMP);
+      case REGR_SLOPE:
+        checkState(inputDataTypes.size() == 2, "Wrong inputDataTypes size.");
+        return new RegressionAccumulator(
+            new TSDataType[] {inputDataTypes.get(0), inputDataTypes.get(1)},
+            RegressionAccumulator.RegressionType.REGR_SLOPE);
+      case REGR_INTERCEPT:
+        checkState(inputDataTypes.size() == 2, "Wrong inputDataTypes size.");
+        return new RegressionAccumulator(
+            new TSDataType[] {inputDataTypes.get(0), inputDataTypes.get(1)},
+            RegressionAccumulator.RegressionType.REGR_INTERCEPT);
       default:
         throw new IllegalArgumentException("Invalid Aggregation function: " + aggregationType);
     }
@@ -140,6 +170,12 @@ private static Accumulator createBuiltinSingleInputAccumulator(
         return new VarianceAccumulator(tsDataType, VarianceAccumulator.VarianceType.VAR_SAMP);
       case VAR_POP:
         return new VarianceAccumulator(tsDataType, VarianceAccumulator.VarianceType.VAR_POP);
+      case SKEWNESS:
+        return new CentralMomentAccumulator(
+            tsDataType, CentralMomentAccumulator.MomentType.SKEWNESS);
+      case KURTOSIS:
+        return new CentralMomentAccumulator(
+            tsDataType, CentralMomentAccumulator.MomentType.KURTOSIS);
       default:
         throw new IllegalArgumentException("Invalid Aggregation function: " + aggregationType);
     }

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/aggregation/CentralMomentAccumulator.java

@@ -0,0 +1,238 @@
+/*
+ * Licensed 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.iotdb.db.queryengine.execution.aggregation;
+
+import org.apache.tsfile.block.column.Column;
+import org.apache.tsfile.block.column.ColumnBuilder;
+import org.apache.tsfile.enums.TSDataType;
+import org.apache.tsfile.file.metadata.statistics.Statistics;
+import org.apache.tsfile.utils.Binary;
+import org.apache.tsfile.utils.BitMap;
+
+import java.nio.ByteBuffer;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+public class CentralMomentAccumulator implements Accumulator {
+
+  public enum MomentType {
+    SKEWNESS,
+    KURTOSIS
+  }
+
+  private final TSDataType seriesDataType;
+  private final MomentType momentType;
+
+  private long count;
+  private double mean;
+  private double m2;
+  private double m3;
+  private double m4;
+
+  public CentralMomentAccumulator(TSDataType seriesDataType, MomentType momentType) {
+    this.seriesDataType = seriesDataType;
+    this.momentType = momentType;
+  }
+
+  @Override
+  public void addInput(Column[] columns, BitMap bitMap) {
+
+    int size = columns[1].getPositionCount();
+    for (int i = 0; i < size; i++) {
+      if (bitMap != null && !bitMap.isMarked(i)) {
+        continue;
+      }
+      if (columns[1].isNull(i)) {
+        continue;
+      }
+      update(getDoubleValue(columns[1], i));
+    }
+  }
+
+  private double getDoubleValue(Column column, int position) {
+    switch (seriesDataType) {
+      case INT32:
+      case DATE:
+        return column.getInt(position);
+      case INT64:
+      case TIMESTAMP:
+        return column.getLong(position);
+      case FLOAT:
+        return column.getFloat(position);
+      case DOUBLE:
+        return column.getDouble(position);
+      default:
+        throw new UnsupportedOperationException(
+            "Unsupported data type in CentralMoment Aggregation: " + seriesDataType);
+    }
+  }
+
+  private void update(double value) {
+    long n1 = count;
+    count++;
+
+    double delta = value - mean;
+    double delta_n = delta / count;
+    double delta_n2 = delta_n * delta_n;
+    double term1 = delta * delta_n * n1;
+
+    mean += delta_n;
+
+    m4 += term1 * delta_n2 * (count * count - 3 * count + 3) + 6 * delta_n2 * m2 - 4 * delta_n * m3;
+
+    m3 += term1 * delta_n * (count - 2) - 3 * delta_n * m2;
+
+    m2 += term1;
+  }
+
+  @Override
+  public void addIntermediate(Column[] partialResult) {
+    checkArgument(partialResult.length == 1, "partialResult of CentralMoment should be 1");
+    if (partialResult[0].isNull(0)) {
+      return;
+    }
+    byte[] bytes = partialResult[0].getBinary(0).getValues();
+    ByteBuffer buffer = ByteBuffer.wrap(bytes);
+
+    long otherCount = buffer.getLong();
+    double otherMean = buffer.getDouble();
+    double otherM2 = buffer.getDouble();
+    double otherM3 = buffer.getDouble();
+    double otherM4 = buffer.getDouble();
+
+    merge(otherCount, otherMean, otherM2, otherM3, otherM4);
+  }
+
+  private void merge(long nB, double meanB, double m2B, double m3B, double m4B) {
+    if (nB == 0) return;
+    if (count == 0) {
+      count = nB;
+      mean = meanB;
+      m2 = m2B;
+      m3 = m3B;
+      m4 = m4B;
+    } else {
+      long nA = count;
+      long nTotal = nA + nB;
+      double delta = meanB - mean;
+      double delta2 = delta * delta;
+      double delta3 = delta * delta2;
+      double delta4 = delta2 * delta2;
+
+      m4 +=
+          m4B
+              + delta4 * nA * nB * (nA * nA - nA * nB + nB * nB) / (nTotal * nTotal * nTotal)
+              + 6.0 * delta2 * (nA * nA * m2B + nB * nB * m2) / (nTotal * nTotal)
+              + 4.0 * delta * (nA * m3B - nB * m3) / nTotal;
+
+      m3 +=
+          m3B
+              + delta3 * nA * nB * (nA - nB) / (nTotal * nTotal)
+              + 3.0 * delta * (nA * m2B - nB * m2) / nTotal;
+
+      m2 += m2B + delta2 * nA * nB / nTotal;
+
+      mean += delta * nB / nTotal;
+      count = nTotal;
+    }
+  }
+
+  @Override
+  public void outputIntermediate(ColumnBuilder[] columnBuilders) {
+    checkArgument(columnBuilders.length == 1, "partialResult should be 1");
+    if (count == 0) {
+      columnBuilders[0].appendNull();
+    } else {
+
+      byte[] bytes = new byte[40];
+      ByteBuffer buffer = ByteBuffer.wrap(bytes);
+      buffer.putLong(count);
+      buffer.putDouble(mean);
+      buffer.putDouble(m2);
+      buffer.putDouble(m3);
+      buffer.putDouble(m4);
+      columnBuilders[0].writeBinary(new Binary(bytes));
+    }
+  }
+
+  @Override
+  public void outputFinal(ColumnBuilder columnBuilder) {
+    if (count == 0 || m2 == 0) {
+      columnBuilder.appendNull();
+      return;
+    }
+
+    if (momentType == MomentType.SKEWNESS) {
+      if (count < 3) {
+        columnBuilder.appendNull();
+      } else {
+
+        double variance = m2 / (count - 1);
+        double stdev = Math.sqrt(variance);
+        double result = (count * m3) / ((count - 1) * (count - 2) * stdev * stdev * stdev);
+        columnBuilder.writeDouble(result);
+      }
+    } else {
+      if (count < 4) {
+        columnBuilder.appendNull();
+      } else {
+
+        double variance = m2 / (count - 1);
+        double term1 =
+            (count * (count + 1) * m4)
+                / ((count - 1) * (count - 2) * (count - 3) * variance * variance);
+        double term2 = (3 * Math.pow(count - 1, 2)) / ((count - 2) * (count - 3));
+        columnBuilder.writeDouble(term1 - term2);
+      }
+    }
+  }
+
+  @Override
+  public void removeIntermediate(Column[] input) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public void addStatistics(Statistics statistics) {
+    throw new UnsupportedOperationException();
+  }
+
+  @Override
+  public void setFinal(Column finalResult) {}
+
+  @Override
+  public void reset() {
+    count = 0;
+    mean = 0;
+    m2 = 0;
+    m3 = 0;
+    m4 = 0;
+  }
+
+  @Override
+  public boolean hasFinalResult() {
+    return false;
+  }
+
+  @Override
+  public TSDataType[] getIntermediateType() {
+    return new TSDataType[] {TSDataType.TEXT};
+  }
+
+  @Override
+  public TSDataType getFinalType() {
+    return TSDataType.DOUBLE;
+  }
+}