[GitHub] [druid] clintropolis commented on a diff in pull request #12277: add support for 'front coded' string dictionaries for smaller string columns

[GitBox <gi...@apache.org>]

clintropolis commented on code in PR #12277:
URL: https://github.com/apache/druid/pull/12277#discussion_r979031643


##########
processing/src/main/java/org/apache/druid/segment/column/StringFrontCodedDictionaryEncodedColumn.java:
##########
@@ -0,0 +1,598 @@
+/*
+ * 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.column;
+
+import com.google.common.base.Predicate;
+import com.google.common.base.Predicates;
+import org.apache.druid.java.util.common.StringUtils;
+import org.apache.druid.query.extraction.ExtractionFn;
+import org.apache.druid.query.filter.ValueMatcher;
+import org.apache.druid.query.monomorphicprocessing.RuntimeShapeInspector;
+import org.apache.druid.segment.AbstractDimensionSelector;
+import org.apache.druid.segment.DimensionSelectorUtils;
+import org.apache.druid.segment.IdLookup;
+import org.apache.druid.segment.data.ColumnarInts;
+import org.apache.druid.segment.data.ColumnarMultiInts;
+import org.apache.druid.segment.data.FrontCodedIndexed;
+import org.apache.druid.segment.data.IndexedInts;
+import org.apache.druid.segment.data.ReadableOffset;
+import org.apache.druid.segment.data.SingleIndexedInt;
+import org.apache.druid.segment.filter.BooleanValueMatcher;
+import org.apache.druid.segment.historical.HistoricalDimensionSelector;
+import org.apache.druid.segment.historical.SingleValueHistoricalDimensionSelector;
+import org.apache.druid.segment.vector.MultiValueDimensionVectorSelector;
+import org.apache.druid.segment.vector.ReadableVectorInspector;
+import org.apache.druid.segment.vector.ReadableVectorOffset;
+import org.apache.druid.segment.vector.SingleValueDimensionVectorSelector;
+import org.apache.druid.segment.vector.VectorObjectSelector;
+import org.apache.druid.utils.CloseableUtils;
+
+import javax.annotation.Nullable;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.BitSet;
+
+/**
+ * {@link DictionaryEncodedColumn<String>} for a column which uses a {@link FrontCodedIndexed} to store its value
+ * dictionary, which 'delta encodes' strings (instead of {@link org.apache.druid.segment.data.GenericIndexed} like
+ * {@link StringDictionaryEncodedColumn}).
+ *
+ * This class is otherwise nearly identical to {@link StringDictionaryEncodedColumn} other than the dictionary

Review Comment:
   i'm a bit sad about this duplication but its a bit tricky to make this an regular string column share stuff because of its use of `GenericIndexed.singleThreaded` and the `CachedIndexed` stuff and this column only uses a the ByteBuffer dictionary, so sharing columns requires a bit more thought on how to do properly, not to mention also probably needs measurement to make sure making the dictionary type generic doesn't have any negative perf impact.
   
   Since there are enough moving parts in this PR already, I'd rather look into this as a follow-up.



-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: commits-unsubscribe@druid.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscribe@druid.apache.org
For additional commands, e-mail: commits-help@druid.apache.org