[CALCITE-4215] Ensure org.apache.calcite.schema.Statistic uses null v…

…s emptyList appropriately null means the statistic is not known, emptyList means the statistic is known, and the value is empty
libenchao · Oct 1, 2020 · 92ea5a2 · 92ea5a2
1 parent 8a7e1be
commit 92ea5a2
Show file tree

Hide file tree

Showing 3 changed files with 33 additions and 69 deletions.
diff --git a/core/src/main/java/org/apache/calcite/schema/Statistic.java b/core/src/main/java/org/apache/calcite/schema/Statistic.java
@@ -32,23 +32,35 @@
  */
 public interface Statistic {
   /** Returns the approximate number of rows in the table. */
-  Double getRowCount();
+  default Double getRowCount() {
+    return null;
+  }
 
   /** Returns whether the given set of columns is a unique key, or a superset
    * of a unique key, of the table.
    */
-  boolean isKey(ImmutableBitSet columns);
+  default boolean isKey(ImmutableBitSet columns) {
+    return false;
+  }
 
   /** Returns a list of unique keys, or null if no key exist. */
-  List<ImmutableBitSet> getKeys();
+  default List<ImmutableBitSet> getKeys() {
+    return null;
+  }
 
   /** Returns the collection of referential constraints (foreign-keys)
    * for this table. */
-  List<RelReferentialConstraint> getReferentialConstraints();
+  default List<RelReferentialConstraint> getReferentialConstraints() {
+    return null;
+  }
 
   /** Returns the collections of columns on which this table is sorted. */
-  List<RelCollation> getCollations();
+  default List<RelCollation> getCollations() {
+    return null;
+  }
 
   /** Returns the distribution of the data in this table. */
-  RelDistribution getDistribution();
+  default RelDistribution getDistribution()  {
+    return null;
+  }
 }
diff --git a/core/src/main/java/org/apache/calcite/schema/Statistics.java b/core/src/main/java/org/apache/calcite/schema/Statistics.java
@@ -17,8 +17,6 @@
 package org.apache.calcite.schema;
 
 import org.apache.calcite.rel.RelCollation;
-import org.apache.calcite.rel.RelDistribution;
-import org.apache.calcite.rel.RelDistributionTraitDef;
 import org.apache.calcite.rel.RelReferentialConstraint;
 import org.apache.calcite.util.ImmutableBitSet;
 
@@ -36,50 +34,27 @@ private Statistics() {
   /** Returns a {@link Statistic} that knows nothing about a table. */
   public static final Statistic UNKNOWN =
       new Statistic() {
-        public Double getRowCount() {
-          return null;
-        }
-
-        public boolean isKey(ImmutableBitSet columns) {
-          return false;
-        }
-
-        public List<ImmutableBitSet> getKeys() {
-          return ImmutableList.of();
-        }
-
-        public List<RelReferentialConstraint> getReferentialConstraints() {
-          return ImmutableList.of();
-        }
-
-        public List<RelCollation> getCollations() {
-          return ImmutableList.of();
-        }
-
-        public RelDistribution getDistribution() {
-          return RelDistributionTraitDef.INSTANCE.getDefault();
-        }
       };
 
   /** Returns a statistic with a given set of referential constraints. */
   public static Statistic of(final List<RelReferentialConstraint> referentialConstraints) {
-    return of(null, ImmutableList.of(),
-        referentialConstraints, ImmutableList.of());
+    return of(null, null,
+        referentialConstraints, null);
   }
 
   /** Returns a statistic with a given row count and set of unique keys. */
   public static Statistic of(final double rowCount,
       final List<ImmutableBitSet> keys) {
-    return of(rowCount, keys, ImmutableList.of(),
-        ImmutableList.of());
+    return of(rowCount, keys, null,
+        null);
   }
 
   /** Returns a statistic with a given row count, set of unique keys,
    * and collations. */
   public static Statistic of(final double rowCount,
       final List<ImmutableBitSet> keys,
       final List<RelCollation> collations) {
-    return of(rowCount, keys, ImmutableList.of(), collations);
+    return of(rowCount, keys, null, collations);
   }
 
   /** Returns a statistic with a given row count, set of unique keys,
@@ -88,13 +63,19 @@ public static Statistic of(final Double rowCount,
       final List<ImmutableBitSet> keys,
       final List<RelReferentialConstraint> referentialConstraints,
       final List<RelCollation> collations) {
+    List<ImmutableBitSet> keysCopy = keys == null ? ImmutableList.of() : ImmutableList.copyOf(keys);
+    List<RelReferentialConstraint> referentialConstraintsCopy =
+        referentialConstraints == null ? null : ImmutableList.copyOf(referentialConstraints);
+    List<RelCollation> collationsCopy =
+        collations == null ? null : ImmutableList.copyOf(collations);
+
     return new Statistic() {
       public Double getRowCount() {
         return rowCount;
       }
 
       public boolean isKey(ImmutableBitSet columns) {
-        for (ImmutableBitSet key : keys) {
+        for (ImmutableBitSet key : keysCopy) {
           if (columns.contains(key)) {
             return true;
           }
@@ -103,19 +84,15 @@ public boolean isKey(ImmutableBitSet columns) {
       }
 
       public List<ImmutableBitSet> getKeys() {
-        return ImmutableList.copyOf(keys);
+        return keysCopy;
       }
 
       public List<RelReferentialConstraint> getReferentialConstraints() {
-        return referentialConstraints;
+        return referentialConstraintsCopy;
       }
 
       public List<RelCollation> getCollations() {
-        return collations;
-      }
-
-      public RelDistribution getDistribution() {
-        return RelDistributionTraitDef.INSTANCE.getDefault();
+        return collationsCopy;
       }
     };
   }

diff --git a/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterStructsTest.java b/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterStructsTest.java
@@ -19,9 +19,6 @@
 import org.apache.calcite.config.CalciteConnectionConfig;
 import org.apache.calcite.jdbc.CalciteSchema;
 import org.apache.calcite.linq4j.tree.Expression;
-import org.apache.calcite.rel.RelCollation;
-import org.apache.calcite.rel.RelDistribution;
-import org.apache.calcite.rel.RelReferentialConstraint;
 import org.apache.calcite.rel.type.RelDataType;
 import org.apache.calcite.rel.type.RelDataTypeFactory;
 import org.apache.calcite.rel.type.RelProtoDataType;
@@ -36,15 +33,13 @@
 import org.apache.calcite.sql.dialect.CalciteSqlDialect;
 import org.apache.calcite.sql.parser.SqlParser;
 import org.apache.calcite.sql.type.SqlTypeName;
-import org.apache.calcite.util.ImmutableBitSet;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 
 import org.junit.jupiter.api.Test;
 
 import java.util.Collection;
-import java.util.List;
 import java.util.Set;
 
 /**
@@ -160,26 +155,6 @@ class RelToSqlConverterStructsTest {
     @Override public Double getRowCount() {
       return 0D;
     }
-
-    @Override public boolean isKey(ImmutableBitSet columns) {
-      return false;
-    }
-
-    @Override public List<ImmutableBitSet> getKeys() {
-      return ImmutableList.of();
-    }
-
-    @Override public List<RelReferentialConstraint> getReferentialConstraints() {
-      return ImmutableList.of();
-    }
-
-    @Override public List<RelCollation> getCollations() {
-      return ImmutableList.of();
-    }
-
-    @Override public RelDistribution getDistribution() {
-      return null;
-    }
   };
 
   private static final SchemaPlus ROOT_SCHEMA = CalciteSchema