Add new 'true' filter which always returns true. (#5711)

* Add new 'true' filter which always returns true.

* Add support for bitmap index.

* Adds documentation.

* Removes No-op Filter

docs/content/querying/filters.md

@@ -488,10 +488,9 @@ Filtering on a set of ISO 8601 intervals:
 }
 ```
 
-
-### Noop Filter
-The noop filter is a filter which applies no conditions to your query.  Useful if you need to disable other filters when queries are generated programatically. 
+### True Filter
+The true filter is a filter which matches all values.  It can be used to temporarily disable other filters without removing the filter. 
 
 ```json
-{ "type" : "noop" }
+{ "type" : "true" }
 ```

processing/src/main/java/io/druid/query/filter/DimFilter.java

@@ -45,7 +45,7 @@ import java.util.HashSet;
     @JsonSubTypes.Type(name = "interval", value = IntervalDimFilter.class),
     @JsonSubTypes.Type(name = "like", value = LikeDimFilter.class),
     @JsonSubTypes.Type(name = "expression", value = ExpressionDimFilter.class),
-    @JsonSubTypes.Type(name = "noop", value = NoopDimFilter.class)
+    @JsonSubTypes.Type(name = "true", value = TrueDimFilter.class)
 })
 public interface DimFilter extends Cacheable
 {

processing/src/main/java/io/druid/query/filter/DimFilterUtils.java

@@ -52,6 +52,7 @@ public class DimFilterUtils
   static final byte LIKE_CACHE_ID = 0xC;
   static final byte COLUMN_COMPARISON_CACHE_ID = 0xD;
   static final byte EXPRESSION_CACHE_ID = 0xE;
+  static final byte TRUE_CACHE_ID = 0xF;
   public static final byte STRING_SEPARATOR = (byte) 0xFF;
 
   static byte[] computeCacheKey(byte cacheIdKey, List<DimFilter> filters)

processing/src/main/java/io/druid/query/filter/TrueDimFilter.java

@@ -0,0 +1,54 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets 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 io.druid.query.filter;
+
+import com.google.common.collect.RangeSet;
+import io.druid.segment.filter.TrueFilter;
+
+import java.nio.ByteBuffer;
+
+/**
+ */
+public class TrueDimFilter implements DimFilter
+{
+  @Override
+  public byte[] getCacheKey()
+  {        
+    return ByteBuffer.allocate(1).put(DimFilterUtils.TRUE_CACHE_ID).array();
+  }
+
+  @Override
+  public DimFilter optimize()
+  {
+    return this;
+  }
+
+  @Override
+  public Filter toFilter()
+  {
+    return new TrueFilter();
+  }
+
+  @Override
+  public RangeSet<String> getDimensionRangeSet(String dimension)
+  {
+    return null;
+  }
+}

processing/src/main/java/io/druid/segment/filter/TrueFilter.java

@@ -0,0 +1,74 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets 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 io.druid.segment.filter;
+
+import io.druid.query.BitmapResultFactory;
+import io.druid.query.filter.BitmapIndexSelector;
+import io.druid.query.filter.Filter;
+import io.druid.query.filter.ValueMatcher;
+import io.druid.segment.ColumnSelector;
+import io.druid.segment.ColumnSelectorFactory;
+
+/**
+ */
+public class TrueFilter implements Filter
+{
+  public TrueFilter()
+  {
+  }
+
+  @Override
+  public <T> T getBitmapResult(BitmapIndexSelector selector, BitmapResultFactory<T> bitmapResultFactory)
+  {
+    return bitmapResultFactory.wrapAllTrue(Filters.allTrue(selector));
+  }
+
+  @Override
+  public ValueMatcher makeMatcher(ColumnSelectorFactory factory)
+  {
+    return TrueValueMatcher.instance();
+  }
+
+  @Override
+  public boolean supportsBitmapIndex(BitmapIndexSelector selector)
+  {
+    return true;
+  }
+
+  @Override
+  public boolean supportsSelectivityEstimation(
+      ColumnSelector columnSelector, BitmapIndexSelector indexSelector
+  )
+  {
+    return true;
+  }
+
+  @Override
+  public double estimateSelectivity(BitmapIndexSelector indexSelector)
+  {
+    return 1;
+  }
+
+  @Override
+  public String toString()
+  {
+    return "true";
+  }
+}