[CARBONDATA-3145] Read improvement for complex column pages while que…

…rying

core/src/main/java/org/apache/carbondata/core/scan/complextypes/ComplexQueryType.java

@@ -18,7 +18,10 @@
 package org.apache.carbondata.core.scan.complextypes;
 
 import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
 
+import org.apache.carbondata.core.datastore.chunk.DimensionColumnPage;
 import org.apache.carbondata.core.datastore.chunk.impl.DimensionRawColumnChunk;
 import org.apache.carbondata.core.scan.processor.RawBlockletColumnChunks;
 
@@ -29,6 +32,8 @@ public class ComplexQueryType {
 
   protected int blockIndex;
 
+  protected Map<Integer, DimensionColumnPage> decodedPagesWithPageNumber = new HashMap<>();
+
   public ComplexQueryType(String name, String parentname, int blockIndex) {
     this.name = name;
     this.parentname = parentname;
@@ -41,8 +46,7 @@ public ComplexQueryType(String name, String parentname, int blockIndex) {
    */
   protected byte[] copyBlockDataChunk(DimensionRawColumnChunk[] rawColumnChunks,
       int rowNumber, int pageNumber) {
-    byte[] data =
-        rawColumnChunks[blockIndex].decodeColumnPage(pageNumber).getChunkData(rowNumber);
+    byte[] data = getDecodedPage(rawColumnChunks[blockIndex], pageNumber).getChunkData(rowNumber);
     byte[] output = new byte[data.length];
     System.arraycopy(data, 0, output, 0, output.length);
     return output;
@@ -57,4 +61,13 @@ protected void readBlockDataChunk(RawBlockletColumnChunks blockChunkHolder) thro
           .readDimensionChunk(blockChunkHolder.getFileReader(), blockIndex);
     }
   }
+
+  private DimensionColumnPage getDecodedPage(DimensionRawColumnChunk dimensionRawColumnChunk,
+      int pageNumber) {
+    if (null == this.decodedPagesWithPageNumber.get(pageNumber)) {
+      this.decodedPagesWithPageNumber
+          .put(pageNumber, dimensionRawColumnChunk.decodeColumnPage(pageNumber));
+    }
+    return this.decodedPagesWithPageNumber.get(pageNumber);
+  }
 }