GAL-617 Druid hdrhistogram扩展添加HDR_DESCRIBE、HDR_GET_PERCENTILES_DESCRIPTION函数

druid-hdrhistogram/src/main/java/org/HdrHistogram/ArrayHistogram.java

@@ -8,9 +8,7 @@ package org.HdrHistogram; /**
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.nio.ByteBuffer;
-import java.util.ArrayList;
+import java.util.*;
-import java.util.Arrays;
-import java.util.List;
 import java.util.zip.DataFormatException;
 
 /**
@@ -305,6 +303,35 @@ public class ArrayHistogram extends AbstractHistogram implements Histogramer{
         return percentiles;
     }
 
+    @Override
+    public Map<String, Object> describe() {
+        long min = getMinValue();
+        long max = getMaxValue(); // max = this.maxValue;
+        long count = getTotalCount();
+        double mean = getMean();
+        long sum = (long) (mean * count);
+        mean = Math.round(mean * 100.0) / 100.0;
+        long p25 = getValueAtPercentile(25);
+        long p50 = getValueAtPercentile(50);
+        long p75 = getValueAtPercentile(75);
+        long p90 = getValueAtPercentile(90);
+        long p95 = getValueAtPercentile(95);
+        long p99 = getValueAtPercentile(99);
+        Map<String, Object> rst = new LinkedHashMap<>();
+        rst.put("count", count);
+        rst.put("mean", mean);
+        rst.put("sum", sum);
+        rst.put("min", min);
+        rst.put("p25", p25);
+        rst.put("p50", p50);
+        rst.put("p75", p75);
+        rst.put("p90", p90);
+        rst.put("p95", p95);
+        rst.put("p99", p99);
+        rst.put("max", max);
+        return rst;
+    }
+
     @Override
     public Histogramer resetHistogram() {
         if(isAutoResize()){

druid-hdrhistogram/src/main/java/org/HdrHistogram/DirectArrayHistogram.java

@@ -2,7 +2,9 @@ package org.HdrHistogram;
 
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 
 public class DirectArrayHistogram extends AbstractHistogram implements Histogramer{
     long totalCount;
@@ -172,6 +174,35 @@ public class DirectArrayHistogram extends AbstractHistogram implements Histogram
         return percentiles;
     }
 
+    @Override
+    public Map<String, Object> describe() {
+        long min = getMinValue();
+        long max = getMaxValue(); // max = this.maxValue;
+        long count = getTotalCount();
+        double mean = getMean();
+        long sum = (long) (mean * count);
+        mean = Math.round(mean * 100.0) / 100.0;
+        long p25 = getValueAtPercentile(25);
+        long p50 = getValueAtPercentile(50);
+        long p75 = getValueAtPercentile(75);
+        long p90 = getValueAtPercentile(90);
+        long p95 = getValueAtPercentile(95);
+        long p99 = getValueAtPercentile(99);
+        Map<String, Object> rst = new LinkedHashMap<>();
+        rst.put("count", count);
+        rst.put("mean", mean);
+        rst.put("sum", sum);
+        rst.put("min", min);
+        rst.put("p25", p25);
+        rst.put("p50", p50);
+        rst.put("p75", p75);
+        rst.put("p90", p90);
+        rst.put("p95", p95);
+        rst.put("p99", p99);
+        rst.put("max", max);
+        return rst;
+    }
+
     @Override
     public Histogramer resetHistogram() {
         throw new UnsupportedOperationException("unsupported method");

druid-hdrhistogram/src/main/java/org/HdrHistogram/DirectMapHistogram.java

@@ -3,6 +3,7 @@ package org.HdrHistogram;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.List;
+import java.util.Map;
 import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
 
@@ -446,6 +447,11 @@ public class DirectMapHistogram implements Histogramer{
         throw new UnsupportedOperationException("unsupported method");
     }
 
+    @Override
+    public Map<String, Object> describe() {
+        throw new UnsupportedOperationException("unsupported method");
+    }
+
     @Override
     public Histogramer resetHistogram() {
         throw new UnsupportedOperationException("unsupported method");

druid-hdrhistogram/src/main/java/org/HdrHistogram/HistogramSketch.java

@@ -2,6 +2,7 @@ package org.HdrHistogram;
 
 import java.nio.ByteBuffer;
 import java.util.List;
+import java.util.Map;
 
 public class HistogramSketch {
     public Histogramer hisImpl = null;
@@ -59,6 +60,10 @@ public class HistogramSketch {
         return hisImpl.percentileList(percentileTicksPerHalfDistance);
     }
 
+    public Map<String, Object> describe(){
+        return hisImpl.describe();
+    }
+
     public static final int getUpdatableSerializationBytes(long lowestDiscernibleValue, long highestTrackableValue, int numberOfSignificantValueDigits){
         return DirectArrayHistogram.getUpdatableSerializationBytes(lowestDiscernibleValue, highestTrackableValue, numberOfSignificantValueDigits);
     }

druid-hdrhistogram/src/main/java/org/HdrHistogram/Histogramer.java

@@ -2,6 +2,7 @@ package org.HdrHistogram;
 
 import java.nio.ByteBuffer;
 import java.util.List;
+import java.util.Map;
 
 public interface Histogramer {
     long getTotalCount();
@@ -14,6 +15,8 @@ public interface Histogramer {
 
     List<Percentile> percentileList(int percentileTicksPerHalfDistance);
 
+    Map<String, Object> describe();
+
     Histogramer resetHistogram();
 
     Histogramer merge(Histogramer histogram);

druid-hdrhistogram/src/main/java/org/HdrHistogram/Percentile.java

@@ -38,4 +38,13 @@ public class Percentile {
     public void setPercentile(double percentile) {
         this.percentile = percentile;
     }
+
+    @Override
+    public String toString() {
+        return "Percentile{" +
+                "value=" + value +
+                ", count=" + count +
+                ", percentile=" + percentile +
+                '}';
+    }
 }

druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramAggregatorFactory.java

@@ -21,7 +21,7 @@ public class HdrHistogramAggregatorFactory extends AggregatorFactory {
     public static final long DEFAULT_HIGHEST = 2;
     public static final int DEFAULT_SIGNIFICANT = 1;
     public static final boolean DEFAULT_AUTO_RESIZE = true;
-    public static final long BUFFER_AUTO_RESIZE_HIGHEST = 100000000L * 1000000L;
+    public static final long BUFFER_AUTO_RESIZE_HIGHEST = 100000000L * 100L;
     public static final Comparator<HistogramSketch> COMPARATOR =
             Comparator.nullsFirst(Comparator.comparingLong(HistogramSketch::getTotalCount));
 

druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramMergeBufferAggregator.java

@@ -37,7 +37,7 @@ public class HdrHistogramMergeBufferAggregator implements BufferAggregator {
         this.numberOfSignificantValueDigits = numberOfSignificantValueDigits;
         this.autoResize = autoResize;
         this.size = size;
-        LOG.error("HdrHistogramMergeBufferAggregator gene:" + Thread.currentThread().getName() + "-" + Thread.currentThread().getId());
+        //LOG.error("HdrHistogramMergeBufferAggregator gene:" + Thread.currentThread().getName() + "-" + Thread.currentThread().getId());
     }
 
     @Override
@@ -83,7 +83,7 @@ public class HdrHistogramMergeBufferAggregator implements BufferAggregator {
     @Nullable
     @Override
     public synchronized HistogramSketch get(ByteBuffer buf, int position) {
-        LOG.error("HdrHistogramMergeBufferAggregator get:" +  0  + "-" + Thread.currentThread().getId() + "-" + this);
+        //LOG.error("HdrHistogramMergeBufferAggregator get:" +  0  + "-" + Thread.currentThread().getId() + "-" + this);
         HistogramUnion union = histograms.get(buf).get(position);
         //return histogram.copy();
         return union.getResult().copy();

druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramModule.java

@@ -9,10 +9,7 @@ import com.google.common.annotations.VisibleForTesting;
 import com.google.inject.Binder;
 import org.HdrHistogram.HistogramSketch;
 import org.apache.druid.initialization.DruidModule;
-import org.apache.druid.query.aggregation.sketch.HdrHistogram.sql.HdrHistogramObjectSqlAggregator;
+import org.apache.druid.query.aggregation.sketch.HdrHistogram.sql.*;
-import org.apache.druid.query.aggregation.sketch.HdrHistogram.sql.HdrHistogramPercentilesOperatorConversion;
-import org.apache.druid.query.aggregation.sketch.HdrHistogram.sql.HdrHistogramQuantileSqlAggregator;
-import org.apache.druid.query.aggregation.sketch.HdrHistogram.sql.HdrHistogramQuantilesOperatorConversion;
 import org.apache.druid.segment.column.ColumnType;
 import org.apache.druid.segment.serde.ComplexMetrics;
 import org.apache.druid.sql.guice.SqlBindings;
@@ -27,6 +24,8 @@ public class HdrHistogramModule implements DruidModule {
     public static final byte QUANTILES_HDRHISTOGRAM_TO_QUANTILE_CACHE_TYPE_ID = 0x03;
     public static final byte QUANTILES_HDRHISTOGRAM_TO_QUANTILES_CACHE_TYPE_ID = 0x04;
     public static final byte QUANTILES_HDRHISTOGRAM_TO_PERCENTILES_CACHE_TYPE_ID = 0x05;
+    public static final byte QUANTILES_HDRHISTOGRAM_TO_DESCRIBE_CACHE_TYPE_ID = 0x06;
+    public static final byte QUANTILES_HDRHISTOGRAM_TO_PERCENTILES_DESCRIBE_CACHE_TYPE_ID = 0x07;
 
     public static final String HDRHISTOGRAM_TYPE_NAME = "HdrHistogramSketch";
     public static final ColumnType TYPE = ColumnType.ofComplex(HDRHISTOGRAM_TYPE_NAME);
@@ -50,6 +49,8 @@ public class HdrHistogramModule implements DruidModule {
 
         SqlBindings.addOperatorConversion(binder, HdrHistogramQuantilesOperatorConversion.class);
         SqlBindings.addOperatorConversion(binder, HdrHistogramPercentilesOperatorConversion.class);
+        SqlBindings.addOperatorConversion(binder, HdrHistogramDescribeOperatorConversion.class);
+        SqlBindings.addOperatorConversion(binder, HdrHistogramPercentilesDescribeOperatorConversion.class);
     }
 
     @Override
@@ -61,7 +62,9 @@ public class HdrHistogramModule implements DruidModule {
                                 new NamedType(HdrHistogramMergeAggregatorFactory.class, "HdrHistogramSketchMerge"),
                                 new NamedType(HdrHistogramToQuantilePostAggregator.class, "HdrHistogramSketchToQuantile"),
                                 new NamedType(HdrHistogramToQuantilesPostAggregator.class, "HdrHistogramSketchToQuantiles"),
-                                new NamedType(HdrHistogramToPercentilesPostAggregator.class, "HdrHistogramSketchToPercentiles")
+                                new NamedType(HdrHistogramToPercentilesPostAggregator.class, "HdrHistogramSketchToPercentiles"),
+                                new NamedType(HdrHistogramToDescribePostAggregator.class, "HdrHistogramSketchToDescribe"),
+                                new NamedType(HdrHistogramToPercentilesDescribePostAggregator.class, "HdrHistogramSketchToPercentilesDescription")
                         ).addSerializer(HistogramSketch.class, new HistogramJsonSerializer())
         );
     }

druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramToDescribePostAggregator.java

@@ -0,0 +1,108 @@
+package org.apache.druid.query.aggregation.sketch.HdrHistogram;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.collect.Sets;
+import org.HdrHistogram.HistogramSketch;
+import org.apache.druid.java.util.common.IAE;
+import org.apache.druid.query.aggregation.AggregatorFactory;
+import org.apache.druid.query.aggregation.PostAggregator;
+import org.apache.druid.query.cache.CacheKeyBuilder;
+import org.apache.druid.segment.ColumnInspector;
+import org.apache.druid.segment.column.ColumnType;
+
+import javax.annotation.Nullable;
+import java.util.*;
+
+public class HdrHistogramToDescribePostAggregator implements PostAggregator {
+    private final String name;
+    private final String fieldName;
+
+    @JsonCreator
+    public HdrHistogramToDescribePostAggregator(
+            @JsonProperty("name") String name,
+            @JsonProperty("fieldName") String fieldName
+    ){
+        this.name = name;
+        this.fieldName = fieldName;
+    }
+
+    @Override
+    public ColumnType getType(ColumnInspector signature){
+        return ColumnType.STRING;
+    }
+
+    @Override
+    @JsonProperty
+    public String getName() {
+        return name;
+    }
+
+    @JsonProperty
+    public String getFieldName() {
+        return fieldName;
+    }
+
+    @Nullable
+    @Override
+    public Object compute(Map<String, Object> values) {
+        HistogramSketch histogram = (HistogramSketch) values.get(fieldName);
+        if(histogram == null){
+            return "{}"; //"[]"
+        }
+        return HdrHistogramModule.toJson(histogram.describe());
+    }
+
+    @Override
+    public Comparator<double[]> getComparator()
+    {
+        throw new IAE("Comparing arrays of quantiles is not supported");
+    }
+
+    @Override
+    public Set<String> getDependentFields()
+    {
+        return Sets.newHashSet(fieldName);
+    }
+
+    @Override
+    public PostAggregator decorate(Map<String, AggregatorFactory> aggregators) {
+        return this;
+    }
+
+    @Override
+    public byte[] getCacheKey() {
+        CacheKeyBuilder builder = new CacheKeyBuilder(HdrHistogramModule.CACHE_TYPE_ID_OFFSET).appendByte(HdrHistogramModule.QUANTILES_HDRHISTOGRAM_TO_DESCRIBE_CACHE_TYPE_ID)
+                .appendString(fieldName);
+        return builder.build();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        HdrHistogramToDescribePostAggregator that = (HdrHistogramToDescribePostAggregator) o;
+
+        return name.equals(that.name) &&
+                fieldName.equals(that.fieldName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, fieldName);
+    }
+
+    @Override
+    public String toString() {
+        return "HdrHistogramToDescribePostAggregator{" +
+                "name='" + name + '\'' +
+                ", fieldName='" + fieldName + '\'' +
+                '}';
+    }
+
+
+}

druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HdrHistogramToPercentilesDescribePostAggregator.java

@@ -0,0 +1,125 @@
+package org.apache.druid.query.aggregation.sketch.HdrHistogram;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.collect.Sets;
+import org.HdrHistogram.HistogramSketch;
+import org.HdrHistogram.Percentile;
+import org.apache.druid.java.util.common.IAE;
+import org.apache.druid.query.aggregation.AggregatorFactory;
+import org.apache.druid.query.aggregation.PostAggregator;
+import org.apache.druid.query.cache.CacheKeyBuilder;
+import org.apache.druid.segment.ColumnInspector;
+import org.apache.druid.segment.column.ColumnType;
+
+import javax.annotation.Nullable;
+import java.util.*;
+
+public class HdrHistogramToPercentilesDescribePostAggregator implements PostAggregator {
+    private final String name;
+    private final String fieldName;
+    private final int percentileTicksPerHalfDistance;
+
+    @JsonCreator
+    public HdrHistogramToPercentilesDescribePostAggregator(
+            @JsonProperty("name") String name,
+            @JsonProperty("fieldName") String fieldName,
+            @JsonProperty("percentileTicksPerHalfDistance") int percentileTicksPerHalfDistance
+    ){
+        this.name = name;
+        this.fieldName = fieldName;
+        this.percentileTicksPerHalfDistance = percentileTicksPerHalfDistance;
+    }
+
+    @Override
+    public ColumnType getType(ColumnInspector signature){
+        return ColumnType.STRING;
+    }
+
+    @Override
+    @JsonProperty
+    public String getName() {
+        return name;
+    }
+
+    @JsonProperty
+    public String getFieldName() {
+        return fieldName;
+    }
+
+    @JsonProperty
+    public int getPercentileTicksPerHalfDistance() {
+        return percentileTicksPerHalfDistance;
+    }
+
+    @Nullable
+    @Override
+    public Object compute(Map<String, Object> values) {
+        HistogramSketch histogram = (HistogramSketch) values.get(fieldName);
+        if(histogram == null){
+            return "{\"percentiles\":[],\"describe\":{}}";
+        }
+        List<Percentile> percentiles = histogram.percentileList(percentileTicksPerHalfDistance);
+        Map<String, Object> describe = histogram.describe();
+        Map<String, Object> rst = new LinkedHashMap<>();
+        rst.put("percentiles", percentiles);
+        rst.put("description", describe);
+        return HdrHistogramModule.toJson(rst);
+    }
+
+    @Override
+    public Comparator<double[]> getComparator()
+    {
+        throw new IAE("Comparing object is not supported");
+    }
+
+    @Override
+    public Set<String> getDependentFields()
+    {
+        return Sets.newHashSet(fieldName);
+    }
+
+    @Override
+    public PostAggregator decorate(Map<String, AggregatorFactory> aggregators) {
+        return this;
+    }
+
+    @Override
+    public byte[] getCacheKey() {
+        CacheKeyBuilder builder = new CacheKeyBuilder(HdrHistogramModule.CACHE_TYPE_ID_OFFSET).appendByte(HdrHistogramModule.QUANTILES_HDRHISTOGRAM_TO_PERCENTILES_DESCRIBE_CACHE_TYPE_ID)
+                .appendString(fieldName);
+        builder.appendInt(percentileTicksPerHalfDistance);
+        return builder.build();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        HdrHistogramToPercentilesDescribePostAggregator that = (HdrHistogramToPercentilesDescribePostAggregator) o;
+
+        return percentileTicksPerHalfDistance == that.percentileTicksPerHalfDistance &&
+                name.equals(that.name) &&
+                fieldName.equals(that.fieldName);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, fieldName, percentileTicksPerHalfDistance);
+    }
+
+    @Override
+    public String toString() {
+        return "HdrHistogramToPercentilesDescribePostAggregator{" +
+                "name='" + name + '\'' +
+                ", fieldName='" + fieldName + '\'' +
+                ", probabilitys=" + percentileTicksPerHalfDistance +
+                '}';
+    }
+
+
+}

druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/sql/HdrHistogramDescribeOperatorConversion.java

@@ -0,0 +1,77 @@
+package org.apache.druid.query.aggregation.sketch.HdrHistogram.sql;
+
+import org.apache.calcite.rex.RexCall;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.sql.SqlFunction;
+import org.apache.calcite.sql.SqlOperator;
+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.PostAggregator;
+import org.apache.druid.query.aggregation.post.FieldAccessPostAggregator;
+import org.apache.druid.query.aggregation.sketch.HdrHistogram.HdrHistogramToDescribePostAggregator;
+import org.apache.druid.segment.column.RowSignature;
+import org.apache.druid.sql.calcite.expression.DruidExpression;
+import org.apache.druid.sql.calcite.expression.OperatorConversions;
+import org.apache.druid.sql.calcite.expression.PostAggregatorVisitor;
+import org.apache.druid.sql.calcite.expression.SqlOperatorConversion;
+import org.apache.druid.sql.calcite.planner.PlannerContext;
+
+import javax.annotation.Nullable;
+import java.util.List;
+
+public class HdrHistogramDescribeOperatorConversion implements SqlOperatorConversion {
+    private static final String FUNCTION_NAME = "HDR_DESCRIBE";
+    private static final SqlFunction SQL_FUNCTION = OperatorConversions
+            .operatorBuilder(StringUtils.toUpperCase(FUNCTION_NAME))
+            .operandTypes(SqlTypeFamily.ANY)
+            .requiredOperands(1)
+            .returnTypeInference(ReturnTypes.explicit(SqlTypeName.VARCHAR))
+            .build();
+
+    @Override
+    public SqlOperator calciteOperator()
+    {
+        return SQL_FUNCTION;
+    }
+
+    @Override
+    public DruidExpression toDruidExpression(
+            PlannerContext plannerContext,
+            RowSignature rowSignature,
+            RexNode rexNode
+    )
+    {
+        return null;
+    }
+
+    @Nullable
+    @Override
+    public PostAggregator toPostAggregator(
+            PlannerContext plannerContext,
+            RowSignature rowSignature,
+            RexNode rexNode,
+            PostAggregatorVisitor postAggregatorVisitor
+    )
+    {
+        final List<RexNode> operands = ((RexCall) rexNode).getOperands();
+        final PostAggregator postAgg = OperatorConversions.toPostAggregator(
+                plannerContext,
+                rowSignature,
+                operands.get(0),
+                postAggregatorVisitor,
+                true
+        );
+
+        if (postAgg == null) {
+            return null;
+        }
+
+
+        return new HdrHistogramToDescribePostAggregator(
+                postAggregatorVisitor.getOutputNamePrefix() + postAggregatorVisitor.getAndIncrementCounter(),
+                ((FieldAccessPostAggregator)postAgg).getFieldName()
+        );
+    }
+}

druid-hdrhistogram/src/main/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/sql/HdrHistogramPercentilesDescribeOperatorConversion.java

@@ -0,0 +1,88 @@
+package org.apache.druid.query.aggregation.sketch.HdrHistogram.sql;
+
+import org.apache.calcite.rex.RexCall;
+import org.apache.calcite.rex.RexLiteral;
+import org.apache.calcite.rex.RexNode;
+import org.apache.calcite.sql.SqlFunction;
+import org.apache.calcite.sql.SqlKind;
+import org.apache.calcite.sql.SqlOperator;
+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.PostAggregator;
+import org.apache.druid.query.aggregation.post.FieldAccessPostAggregator;
+import org.apache.druid.query.aggregation.sketch.HdrHistogram.HdrHistogramToPercentilesDescribePostAggregator;
+import org.apache.druid.segment.column.RowSignature;
+import org.apache.druid.sql.calcite.expression.DruidExpression;
+import org.apache.druid.sql.calcite.expression.OperatorConversions;
+import org.apache.druid.sql.calcite.expression.PostAggregatorVisitor;
+import org.apache.druid.sql.calcite.expression.SqlOperatorConversion;
+import org.apache.druid.sql.calcite.planner.PlannerContext;
+
+import javax.annotation.Nullable;
+import java.util.List;
+
+public class HdrHistogramPercentilesDescribeOperatorConversion implements SqlOperatorConversion {
+    private static final String FUNCTION_NAME = "HDR_GET_PERCENTILES_DESCRIPTION";
+    private static final SqlFunction SQL_FUNCTION = OperatorConversions
+            .operatorBuilder(StringUtils.toUpperCase(FUNCTION_NAME))
+            .operandTypes(SqlTypeFamily.ANY, SqlTypeFamily.NUMERIC)
+            .requiredOperands(1)
+            .returnTypeInference(ReturnTypes.explicit(SqlTypeName.VARCHAR))
+            .build();
+
+    @Override
+    public SqlOperator calciteOperator()
+    {
+        return SQL_FUNCTION;
+    }
+
+    @Override
+    public DruidExpression toDruidExpression(
+            PlannerContext plannerContext,
+            RowSignature rowSignature,
+            RexNode rexNode
+    )
+    {
+        return null;
+    }
+
+    @Nullable
+    @Override
+    public PostAggregator toPostAggregator(
+            PlannerContext plannerContext,
+            RowSignature rowSignature,
+            RexNode rexNode,
+            PostAggregatorVisitor postAggregatorVisitor
+    )
+    {
+        final List<RexNode> operands = ((RexCall) rexNode).getOperands();
+        final PostAggregator postAgg = OperatorConversions.toPostAggregator(
+                plannerContext,
+                rowSignature,
+                operands.get(0),
+                postAggregatorVisitor,
+                true
+        );
+
+        if (postAgg == null) {
+            return null;
+        }
+
+        int percentileTicksPerHalfDistance = 5;
+        if (operands.size() == 2) {
+            if (!operands.get(1).isA(SqlKind.LITERAL)) {
+                return null;
+            }
+
+            percentileTicksPerHalfDistance = RexLiteral.intValue(operands.get(1));
+        }
+
+        return new HdrHistogramToPercentilesDescribePostAggregator(
+                postAggregatorVisitor.getOutputNamePrefix() + postAggregatorVisitor.getAndIncrementCounter(),
+                ((FieldAccessPostAggregator)postAgg).getFieldName(),
+                percentileTicksPerHalfDistance
+        );
+    }
+}

druid-hdrhistogram/src/test/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/HistogramSketchTest.java

@@ -0,0 +1,79 @@
+package org.apache.druid.query.aggregation.sketch.HdrHistogram;
+
+import org.HdrHistogram.DirectArrayHistogram;
+import org.HdrHistogram.HistogramSketch;
+import org.HdrHistogram.Histogramer;
+import org.HdrHistogram.Percentile;
+import org.apache.commons.lang3.StringUtils;
+import org.junit.Test;
+
+import java.io.BufferedWriter;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Random;
+import java.util.concurrent.ThreadLocalRandom;
+
+public class HistogramSketchTest {
+
+    @Test
+    public void describeTest() throws Exception{
+        DirectArrayHistogram histogram = new DirectArrayHistogram(1, 1000000, 3,
+                ByteBuffer.allocate(HistogramSketch.getUpdatableSerializationBytes(1, 1000000, 3)));
+        System.out.println(histogram.describe());
+        for (int i = 0; i < 10000; i++) {
+            histogram.recordValue(i);
+        }
+        System.out.println(histogram.describe());
+        for (Percentile percentile : histogram.percentileList(100)) {
+            System.out.println(percentile);
+        }
+    }
+
+    @Test
+    public void describeTest1() throws Exception{
+        HistogramSketch histogram = new HistogramSketch(1);
+        System.out.println(histogram.describe());
+        for (int i = 0; i < 10000; i++) {
+            histogram.recordValue(i);
+        }
+        System.out.println(histogram.describe());
+        for (Percentile percentile : histogram.percentileList(100)) {
+            System.out.println(percentile);
+        }
+        System.out.println(StringUtils.repeat('#', 100));
+        histogram = new HistogramSketch(1);
+        for (int i = 0; i < 10000; i++) {
+            histogram.recordValue(ThreadLocalRandom.current().nextLong(100000));
+        }
+        System.out.println(histogram.describe());
+        for (Percentile percentile : histogram.percentileList(100)) {
+            System.out.println(percentile);
+        }
+    }
+
+    @Test
+    public void describeTest3() throws Exception{
+        HistogramSketch histogram = new HistogramSketch(3);
+        System.out.println(histogram.describe());
+        for (int i = 0; i < 10000; i++) {
+            histogram.recordValue(i);
+        }
+        System.out.println(histogram.describe());
+        for (Percentile percentile : histogram.percentileList(100)) {
+            System.out.println(percentile);
+        }
+        System.out.println(StringUtils.repeat('#', 100));
+        histogram = new HistogramSketch(3);
+        for (int i = 0; i < 10000; i++) {
+            histogram.recordValue(ThreadLocalRandom.current().nextLong(100000));
+        }
+        System.out.println(histogram.describe());
+        for (Percentile percentile : histogram.percentileList(100)) {
+            System.out.println(percentile);
+        }
+    }
+
+}

druid-hdrhistogram/src/test/java/org/apache/druid/query/aggregation/sketch/HdrHistogram/sql/HdrHistogramQuantileSqlAggregatorTest.java

@@ -219,6 +219,30 @@ public class HdrHistogramQuantileSqlAggregatorTest extends BaseCalciteQueryTest
         }
     }
 
+    @Test
+    public void testSqlDESCRIBE() throws Exception {
+        String sql = "select HDR_GET_QUANTILES(HDR_HISTOGRAM(m1, 1, 100, 2), 0, 0.25, 0.5, 0.75, 1) a, HDR_DESCRIBE(HDR_HISTOGRAM(m1, 1, 100, 2)) b, HDR_DESCRIBE(HDR_HISTOGRAM(hist_m1, 1, 100, 2)) c from druid.foo";
+        QueryTestBuilder builder = testBuilder().sql(sql).skipVectorize();
+        builder.run();
+        QueryTestRunner.QueryResults queryResults = builder.results();
+        List<Object[]> results = queryResults.results;
+        for (Object[] result : results) {
+            System.out.println(Arrays.toString(result));
+        }
+    }
+
+    @Test
+    public void testSqlDESCRIBE2() throws Exception {
+        String sql = "select HDR_GET_QUANTILES(HDR_HISTOGRAM(m1, 1, 100, 2), 0, 0.25, 0.5, 0.75, 1) a, HDR_GET_PERCENTILES_DESCRIPTION(HDR_HISTOGRAM(m1, 1, 100, 2)) b, HDR_GET_PERCENTILES_DESCRIPTION(HDR_HISTOGRAM(hist_m1, 1, 100, 2)) c from druid.foo";
+        QueryTestBuilder builder = testBuilder().sql(sql).skipVectorize();
+        builder.run();
+        QueryTestRunner.QueryResults queryResults = builder.results();
+        List<Object[]> results = queryResults.results;
+        for (Object[] result : results) {
+            System.out.println(Arrays.toString(result));
+        }
+    }
+
     @Test
     public void testSqlQuery() throws Exception {
         String[] columns = new String[]{"__time", "dim1", "dim2", "dim3", "cnt", "hist_m1", "m1"};