refactor: split out PhysicalSegmentColumnInspector from PhysicalSegmentInspector

Author: clintropolis

benchmarks/src/test/java/org/apache/druid/benchmark/query/SqlBaseBenchmark.java

@@ -65,6 +65,7 @@
 import org.apache.druid.segment.AutoTypeColumnSchema;
 import org.apache.druid.segment.IncrementalIndexSegment;
 import org.apache.druid.segment.IndexSpec;
+import org.apache.druid.segment.PhysicalSegmentColumnInspector;
 import org.apache.druid.segment.PhysicalSegmentInspector;
 import org.apache.druid.segment.QueryableIndex;
 import org.apache.druid.segment.QueryableIndexCursorFactory;
@@ -521,7 +522,7 @@ public SegmentId getId()
             public <T> T as(@Nonnull Class<T> clazz)
             {
               // computed sql schema uses segment metadata, which relies on physical inspector, use the underlying index
-              if (clazz.equals(PhysicalSegmentInspector.class)) {
+              if (clazz.equals(PhysicalSegmentInspector.class) || clazz.equals(PhysicalSegmentColumnInspector.class)) {
                 return (T) new QueryableIndexPhysicalSegmentInspector(index);
               }
               return super.as(clazz);
@@ -548,7 +549,7 @@ public SegmentId getId()
             public <T> T as(@Nonnull Class<T> clazz)
             {
               // computed sql schema uses segment metadata, which relies on physical inspector, use the underlying index
-              if (clazz.equals(PhysicalSegmentInspector.class)) {
+              if (clazz.equals(PhysicalSegmentInspector.class) || clazz.equals(PhysicalSegmentColumnInspector.class)) {
                 return (T) new QueryableIndexPhysicalSegmentInspector(index);
               }
               return super.as(clazz);

multi-stage-query/src/test/java/org/apache/druid/msq/test/MSQTestBase.java

@@ -145,6 +145,7 @@
 import org.apache.druid.segment.CursorFactory;
 import org.apache.druid.segment.IndexBuilder;
 import org.apache.druid.segment.IndexIO;
+import org.apache.druid.segment.PhysicalSegmentColumnInspector;
 import org.apache.druid.segment.PhysicalSegmentInspector;
 import org.apache.druid.segment.QueryableIndex;
 import org.apache.druid.segment.QueryableIndexCursorFactory;
@@ -791,7 +792,7 @@ public <T> T as(@Nonnull Class<T> clazz)
         {
           if (CursorFactory.class.equals(clazz)) {
             return (T) new QueryableIndexCursorFactory(index);
-          } else if (PhysicalSegmentInspector.class.equals(clazz)) {
+          } else if (PhysicalSegmentInspector.class.equals(clazz) || PhysicalSegmentColumnInspector.class.equals(clazz)) {
             return (T) new QueryableIndexPhysicalSegmentInspector(index);
           } else if (QueryableIndex.class.equals(clazz)) {
             return (T) index;

processing/src/main/java/org/apache/druid/query/metadata/SegmentAnalyzer.java

@@ -31,6 +31,7 @@
 import org.apache.druid.segment.CursorFactory;
 import org.apache.druid.segment.CursorHolder;
 import org.apache.druid.segment.DimensionSelector;
+import org.apache.druid.segment.PhysicalSegmentColumnInspector;
 import org.apache.druid.segment.PhysicalSegmentInspector;
 import org.apache.druid.segment.QueryableIndex;
 import org.apache.druid.segment.Segment;
@@ -90,8 +91,9 @@ public Map<String, ColumnAnalysis> analyze(Segment segment)
   {
     Preconditions.checkNotNull(segment, "segment");
     final PhysicalSegmentInspector segmentInspector = segment.as(PhysicalSegmentInspector.class);
+    final PhysicalSegmentColumnInspector columnInspector = segment.as(PhysicalSegmentColumnInspector.class);
 
-    // index is null for incremental-index-based segments, but segmentInspector should always be available
+    // index is null for incremental-index-based segments, but the inspectors should always be available
     final QueryableIndex index = segment.as(QueryableIndex.class);
     final CursorFactory cursorFactory = Objects.requireNonNull(segment.as(CursorFactory.class));
 
@@ -104,8 +106,8 @@ public Map<String, ColumnAnalysis> analyze(Segment segment)
     for (String columnName : rowSignature.getColumnNames()) {
       final ColumnCapabilities capabilities;
 
-      if (segmentInspector != null) {
-        capabilities = segmentInspector.getColumnCapabilities(columnName);
+      if (columnInspector != null) {
+        capabilities = columnInspector.getColumnCapabilities(columnName);
       } else {
         capabilities = null;
       }
@@ -135,7 +137,7 @@ public Map<String, ColumnAnalysis> analyze(Segment segment)
             if (index != null) {
               analysis = analyzeStringColumn(capabilities, index.getColumnHolder(columnName));
             } else {
-              analysis = analyzeStringColumn(capabilities, segmentInspector, cursorFactory, columnName);
+              analysis = analyzeStringColumn(capabilities, columnInspector, cursorFactory, columnName);
             }
             break;
           case ARRAY:
@@ -260,7 +262,7 @@ private ColumnAnalysis analyzeStringColumn(
 
   private ColumnAnalysis analyzeStringColumn(
       final ColumnCapabilities capabilities,
-      @Nullable final PhysicalSegmentInspector analysisInspector,
+      @Nullable final PhysicalSegmentColumnInspector analysisInspector,
       final CursorFactory cursorFactory,
       final String columnName
   )

processing/src/main/java/org/apache/druid/segment/IncrementalIndexSegment.java

@@ -64,7 +64,7 @@ public <T> T as(final Class<T> clazz)
       return (T) new IncrementalIndexMaxIngestedEventTimeInspector(index);
     } else if (Metadata.class.equals(clazz)) {
       return (T) index.getMetadata();
-    } else if (PhysicalSegmentInspector.class.equals(clazz)) {
+    } else if (PhysicalSegmentInspector.class.equals(clazz) || PhysicalSegmentColumnInspector.class.equals(clazz)) {
       return (T) new IncrementalIndexPhysicalSegmentInspector(index);
     } else if (TopNOptimizationInspector.class.equals(clazz)) {
       return (T) new SimpleTopNOptimizationInspector(true);

processing/src/main/java/org/apache/druid/segment/PhysicalSegmentColumnInspector.java

@@ -0,0 +1,52 @@
+/*
+ * 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.segment;
+
+import javax.annotation.Nullable;
+
+/**
+ * Interface for methods describing the columns of physical segments such as {@link QueryableIndexSegment} and
+ * {@link IncrementalIndexSegment} that is not typically used at query time (outside of metadata queries).
+ * <p>
+ * For general metadata information about a segment that is not column specific, use {@link PhysicalSegmentInspector}
+ * instead.
+ */
+public interface PhysicalSegmentColumnInspector extends ColumnInspector
+{
+  /**
+   * Returns the minimum value of the provided column, if known through an index, dictionary, or cache. Returns null
+   * if not known. Does not scan the column to find the minimum value.
+   */
+  @Nullable
+  Comparable getMinValue(String column);
+
+  /**
+   * Returns the minimum value of the provided column, if known through an index, dictionary, or cache. Returns null
+   * if not known. Does not scan the column to find the maximum value.
+   */
+  @Nullable
+  Comparable getMaxValue(String column);
+
+  /**
+   * Returns the number of distinct values in a column, if known, or
+   * {@link DimensionDictionarySelector#CARDINALITY_UNKNOWN} if not.
+   */
+  int getDimensionCardinality(String column);
+}

processing/src/main/java/org/apache/druid/segment/PhysicalSegmentInspector.java

@@ -24,33 +24,16 @@
 /**
  * Interface for methods describing physical segments such as {@link QueryableIndexSegment} and
  * {@link IncrementalIndexSegment} that is not typically used at query time (outside of metadata queries).
+ * <p>
+ * For metadata information about specific columns, use {@link PhysicalSegmentColumnInspector}.
  */
-public interface PhysicalSegmentInspector extends ColumnInspector
+public interface PhysicalSegmentInspector
 {
   /**
    * Returns {@link Metadata} which contains details about how the segment was created
    */
   @Nullable
   Metadata getMetadata();
-  /**
-   * Returns the minimum value of the provided column, if known through an index, dictionary, or cache. Returns null
-   * if not known. Does not scan the column to find the minimum value.
-   */
-  @Nullable
-  Comparable getMinValue(String column);
-
-  /**
-   * Returns the minimum value of the provided column, if known through an index, dictionary, or cache. Returns null
-   * if not known. Does not scan the column to find the maximum value.
-   */
-  @Nullable
-  Comparable getMaxValue(String column);
-
-  /**
-   * Returns the number of distinct values in a column, if known, or
-   * {@link DimensionDictionarySelector#CARDINALITY_UNKNOWN} if not.}
-   */
-  int getDimensionCardinality(String column);
 
   /**
    * Returns the number of rows in the segment

processing/src/main/java/org/apache/druid/segment/QueryableIndexPhysicalSegmentInspector.java

@@ -30,7 +30,7 @@
 import java.io.IOException;
 import java.io.UncheckedIOException;
 
-public class QueryableIndexPhysicalSegmentInspector implements PhysicalSegmentInspector
+public class QueryableIndexPhysicalSegmentInspector implements PhysicalSegmentInspector, PhysicalSegmentColumnInspector
 {
   private final QueryableIndex index;
 

processing/src/main/java/org/apache/druid/segment/QueryableIndexSegment.java

@@ -91,7 +91,7 @@ public <T> T as(@Nonnull Class<T> clazz)
       return (T) timeBoundaryInspector;
     } else if (Metadata.class.equals(clazz)) {
       return (T) index.getMetadata();
-    } else if (PhysicalSegmentInspector.class.equals(clazz)) {
+    } else if (PhysicalSegmentInspector.class.equals(clazz) || PhysicalSegmentColumnInspector.class.equals(clazz)) {
       return (T) new QueryableIndexPhysicalSegmentInspector(index);
     } else if (TopNOptimizationInspector.class.equals(clazz)) {
       return (T) new SimpleTopNOptimizationInspector(true);

processing/src/main/java/org/apache/druid/segment/Segment.java

@@ -68,6 +68,7 @@ public interface Segment extends Closeable
    *   <li> {@link IndexedTable}, table object, if this is a joinable indexed table.
    *   <li> {@link TimeBoundaryInspector}, inspector for min/max timestamps, if supported by this segment.
    *   <li> {@link PhysicalSegmentInspector}, inspector for physical segment details, if supported by this segment.
+   *   <li> {@link PhysicalSegmentColumnInspector}, inspector for physical segment column details, if supported by this segment.
    *   <li> {@link MaxIngestedEventTimeInspector}, inspector for {@link DataSourceMetadataResultValue#getMaxIngestedEventTime()}
    *   <li> {@link TopNOptimizationInspector}, inspector containing information for topN specific optimizations
    *   <li> {@link CloseableShapeshifter}, stepping stone to {@link org.apache.druid.query.rowsandcols.RowsAndColumns}.

processing/src/main/java/org/apache/druid/segment/incremental/IncrementalIndexPhysicalSegmentInspector.java

@@ -22,14 +22,16 @@
 import org.apache.druid.segment.DimensionDictionarySelector;
 import org.apache.druid.segment.DimensionIndexer;
 import org.apache.druid.segment.Metadata;
+import org.apache.druid.segment.PhysicalSegmentColumnInspector;
 import org.apache.druid.segment.PhysicalSegmentInspector;
 import org.apache.druid.segment.column.ColumnCapabilities;
 import org.apache.druid.segment.column.ColumnCapabilitiesImpl;
 import org.apache.druid.segment.column.ColumnHolder;
 
 import javax.annotation.Nullable;
 
-public class IncrementalIndexPhysicalSegmentInspector implements PhysicalSegmentInspector
+public class IncrementalIndexPhysicalSegmentInspector
+    implements PhysicalSegmentInspector, PhysicalSegmentColumnInspector
 {
   static final ColumnCapabilities.CoercionLogic SNAPSHOT_COERCE_LOGIC =
       new ColumnCapabilities.CoercionLogic()