Github user ravipesala commented on a diff in the pull request:
https://github.com/apache/carbondata/pull/2402#discussion_r197820697
--- Diff:
core/src/main/java/org/apache/carbondata/core/localdictionary/PageLevelDictionary.java
---
@@ -0,0 +1,118 @@
+/*
+ * 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.carbondata.core.localdictionary;
+
+import java.io.IOException;
+import java.util.BitSet;
+
+import org.apache.carbondata.core.constants.CarbonCommonConstants;
+import org.apache.carbondata.core.datastore.ColumnType;
+import org.apache.carbondata.core.datastore.TableSpec;
+import org.apache.carbondata.core.datastore.page.ColumnPage;
+import
org.apache.carbondata.core.datastore.page.encoding.ColumnPageEncoder;
+import
org.apache.carbondata.core.datastore.page.encoding.compress.DirectCompressCodec;
+import
org.apache.carbondata.core.datastore.page.statistics.DummyStatsCollector;
+import
org.apache.carbondata.core.localdictionary.exception.DictionaryThresholdReachedException;
+import
org.apache.carbondata.core.localdictionary.generator.LocalDictionaryGenerator;
+import org.apache.carbondata.core.memory.MemoryException;
+import org.apache.carbondata.core.metadata.datatype.DataTypes;
+import org.apache.carbondata.format.LocalDictionaryChunk;
+
+/**
+ * Class to maintain page level dictionary. It will store all unique
dictionary values
+ * used in a page. This is required while writing blocklet level
dictionary in carbondata
+ * file
+ */
+public class PageLevelDictionary {
+
+ /**
+ * dictionary generator to generate dictionary values for page data
+ */
+ private LocalDictionaryGenerator localDictionaryGenerator;
+
+ /**
+ * set of dictionary surrogate key in this page
+ */
+ private BitSet usedDictionaryValues;
+
+ private int maxDictValue;
+
+ private String columnName;
+
+ public PageLevelDictionary(LocalDictionaryGenerator
localDictionaryGenerator,String columnName) {
+ this.localDictionaryGenerator = localDictionaryGenerator;
+ this.usedDictionaryValues = new BitSet();
+ this.columnName = columnName;
+ }
+
+ /**
+ * Below method will be used to get the dictionary value
+ *
+ * @param data column data
+ * @return dictionary value
+ * @throws DictionaryThresholdReachedException when threshold crossed
for column
+ */
+ public int getDictionaryValue(byte[] data) throws
DictionaryThresholdReachedException {
+ int dictionaryValue =
localDictionaryGenerator.generateDictionary(data);
+ this.usedDictionaryValues.set(dictionaryValue);
+ if (maxDictValue < dictionaryValue) {
+ maxDictValue = dictionaryValue;
+ }
+ return dictionaryValue;
+ }
+
+ /**
+ * Method to merge the dictionary value across pages
+ *
+ * @param pageLevelDictionary other page level dictionary
+ */
+ public void mergerDictionaryValues(PageLevelDictionary
pageLevelDictionary) {
+ usedDictionaryValues.and(pageLevelDictionary.usedDictionaryValues);
+ }
+
+ /**
+ * Below method will be used to get the local dictionary chunk for
writing
+ * @TODO Support for numeric data type dictionary exclude columns
+ * @return encoded local dictionary chunk
+ * @throws MemoryException
+ * in case of problem in encoding
+ * @throws IOException
+ * in case of problem in encoding
+ */
+ public LocalDictionaryChunk getLocalDictionaryChunkForBlocklet()
+ throws MemoryException, IOException {
+ // TODO support for actual data type dictionary ColumnSPEC
+ TableSpec.ColumnSpec spec = TableSpec.ColumnSpec
+ .newInstance(columnName, DataTypes.BYTE_ARRAY,
ColumnType.PLAIN_VALUE);
+ ColumnPage dictionaryColumnPage = ColumnPage.newPage(spec,
DataTypes.BYTE_ARRAY, maxDictValue);
+ // TODO support data type specific stats collector for numeric data
types
+ dictionaryColumnPage.setStatsCollector(new DummyStatsCollector());
+ int rowId = 0;
+ //starting index is 1 as dictionary value starts from 1
+ for (int i = 1; i <= maxDictValue; i++) {
+ if (usedDictionaryValues.get(i)) {
+ dictionaryColumnPage
+ .putData(rowId++,
localDictionaryGenerator.getDictionaryKeyBasedOnValue(i));
+ } else {
+ dictionaryColumnPage
+ .putData(rowId++, CarbonCommonConstants.EMPTY_BYTE_ARRAY);
--- End diff --
Check any other cases in data we get empty binary.
---
