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Posted to commits@phoenix.apache.org by sa...@apache.org on 2016/11/04 22:14:15 UTC

[48/50] [abbrv] phoenix git commit: Fail-fast iterators for EncodedColumnQualifierCellsList. Use list iterators instead of get(index) for navigating lists. Use HBase bytes utility for encoded column names. Fix test failures for immutable tables and index

http://git-wip-us.apache.org/repos/asf/phoenix/blob/ede568e9/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/MetaDataEndpointImpl.java
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diff --git a/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/MetaDataEndpointImpl.java b/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/MetaDataEndpointImpl.java
index 9a7b9e3..93a87ea 100644
--- a/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/MetaDataEndpointImpl.java
+++ b/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/MetaDataEndpointImpl.java
@@ -27,6 +27,7 @@ import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.CLASS_NAME_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.COLUMN_COUNT_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.COLUMN_DEF_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.COLUMN_NAME_INDEX;
+import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.COLUMN_QUALIFIER_COUNTER_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.COLUMN_SIZE_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.DATA_TABLE_NAME_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.DATA_TYPE_BYTES;
@@ -34,6 +35,7 @@ import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.DECIMAL_DIGITS_BYT
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.DEFAULT_COLUMN_FAMILY_NAME_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.DEFAULT_VALUE_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.DISABLE_WAL_BYTES;
+import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.ENCODED_COLUMN_QUALIFIER_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.FAMILY_NAME_INDEX;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.IMMUTABLE_ROWS_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.INDEX_DISABLE_TIMESTAMP_BYTES;
@@ -57,6 +59,7 @@ import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.RETURN_TYPE_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.SALT_BUCKETS_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.SCHEMA_NAME_INDEX;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.SORT_ORDER_BYTES;
+import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.STORAGE_SCHEME_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.STORE_NULLS_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.TABLE_FAMILY_BYTES;
 import static org.apache.phoenix.jdbc.PhoenixDatabaseMetaData.TABLE_NAME_INDEX;
@@ -74,11 +77,11 @@ import static org.apache.phoenix.query.QueryConstants.DIVERGED_VIEW_BASE_COLUMN_
 import static org.apache.phoenix.query.QueryConstants.SEPARATOR_BYTE_ARRAY;
 import static org.apache.phoenix.schema.PTableType.INDEX;
 import static org.apache.phoenix.util.ByteUtil.EMPTY_BYTE_ARRAY;
+import static org.apache.phoenix.util.EncodedColumnsUtil.getEncodedColumnQualifier;
 import static org.apache.phoenix.util.SchemaUtil.getVarCharLength;
 import static org.apache.phoenix.util.SchemaUtil.getVarChars;
 
 import java.io.IOException;
-import java.sql.DriverManager;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.sql.Statement;
@@ -150,14 +153,12 @@ import org.apache.phoenix.coprocessor.generated.MetaDataProtos.GetVersionRequest
 import org.apache.phoenix.coprocessor.generated.MetaDataProtos.GetVersionResponse;
 import org.apache.phoenix.coprocessor.generated.MetaDataProtos.MetaDataResponse;
 import org.apache.phoenix.coprocessor.generated.MetaDataProtos.UpdateIndexStateRequest;
-import org.apache.phoenix.expression.ColumnExpression;
 import org.apache.phoenix.expression.Expression;
 import org.apache.phoenix.expression.KeyValueColumnExpression;
 import org.apache.phoenix.expression.LiteralExpression;
 import org.apache.phoenix.expression.ProjectedColumnExpression;
 import org.apache.phoenix.expression.RowKeyColumnExpression;
 import org.apache.phoenix.expression.visitor.StatelessTraverseAllExpressionVisitor;
-import org.apache.phoenix.hbase.index.covered.update.ColumnReference;
 import org.apache.phoenix.hbase.index.util.GenericKeyValueBuilder;
 import org.apache.phoenix.hbase.index.util.ImmutableBytesPtr;
 import org.apache.phoenix.hbase.index.util.KeyValueBuilder;
@@ -190,8 +191,10 @@ import org.apache.phoenix.schema.PMetaDataEntity;
 import org.apache.phoenix.schema.PName;
 import org.apache.phoenix.schema.PNameFactory;
 import org.apache.phoenix.schema.PTable;
+import org.apache.phoenix.schema.PTable.EncodedCQCounter;
 import org.apache.phoenix.schema.PTable.IndexType;
 import org.apache.phoenix.schema.PTable.LinkType;
+import org.apache.phoenix.schema.PTable.StorageScheme;
 import org.apache.phoenix.schema.PTable.ViewType;
 import org.apache.phoenix.schema.PTableImpl;
 import org.apache.phoenix.schema.PTableType;
@@ -209,10 +212,12 @@ import org.apache.phoenix.schema.types.PDataType;
 import org.apache.phoenix.schema.types.PInteger;
 import org.apache.phoenix.schema.types.PLong;
 import org.apache.phoenix.schema.types.PSmallint;
+import org.apache.phoenix.schema.types.PTinyint;
 import org.apache.phoenix.schema.types.PVarbinary;
 import org.apache.phoenix.schema.types.PVarchar;
 import org.apache.phoenix.trace.util.Tracing;
 import org.apache.phoenix.util.ByteUtil;
+import org.apache.phoenix.util.EncodedColumnsUtil;
 import org.apache.phoenix.util.EnvironmentEdgeManager;
 import org.apache.phoenix.util.IndexUtil;
 import org.apache.phoenix.util.KeyValueUtil;
@@ -282,6 +287,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
             TABLE_FAMILY_BYTES, IS_NAMESPACE_MAPPED_BYTES);
     private static final KeyValue AUTO_PARTITION_SEQ_KV = createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, AUTO_PARTITION_SEQ_BYTES);
     private static final KeyValue APPEND_ONLY_SCHEMA_KV = createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, APPEND_ONLY_SCHEMA_BYTES);
+    private static final KeyValue STORAGE_SCHEME_KV = createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, STORAGE_SCHEME_BYTES);
     
     private static final List<KeyValue> TABLE_KV_COLUMNS = Arrays.<KeyValue>asList(
             EMPTY_KEYVALUE_KV,
@@ -308,7 +314,8 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
             UPDATE_CACHE_FREQUENCY_KV,
             IS_NAMESPACE_MAPPED_KV,
             AUTO_PARTITION_SEQ_KV,
-            APPEND_ONLY_SCHEMA_KV
+            APPEND_ONLY_SCHEMA_KV,
+            STORAGE_SCHEME_KV
             );
     static {
         Collections.sort(TABLE_KV_COLUMNS, KeyValue.COMPARATOR);
@@ -338,6 +345,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
     private static final int IS_NAMESPACE_MAPPED_INDEX = TABLE_KV_COLUMNS.indexOf(IS_NAMESPACE_MAPPED_KV);
     private static final int AUTO_PARTITION_SEQ_INDEX = TABLE_KV_COLUMNS.indexOf(AUTO_PARTITION_SEQ_KV);
     private static final int APPEND_ONLY_SCHEMA_INDEX = TABLE_KV_COLUMNS.indexOf(APPEND_ONLY_SCHEMA_KV);
+    private static final int STORAGE_SCHEME_INDEX = TABLE_KV_COLUMNS.indexOf(STORAGE_SCHEME_KV);
 
     // KeyValues for Column
     private static final KeyValue DECIMAL_DIGITS_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, DECIMAL_DIGITS_BYTES);
@@ -351,6 +359,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
     private static final KeyValue IS_VIEW_REFERENCED_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, IS_VIEW_REFERENCED_BYTES);
     private static final KeyValue COLUMN_DEF_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, COLUMN_DEF_BYTES);
     private static final KeyValue IS_ROW_TIMESTAMP_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, IS_ROW_TIMESTAMP_BYTES);
+    private static final KeyValue ENCODED_COLUMN_QUALIFIER_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, ENCODED_COLUMN_QUALIFIER_BYTES);
     private static final List<KeyValue> COLUMN_KV_COLUMNS = Arrays.<KeyValue>asList(
             DECIMAL_DIGITS_KV,
             COLUMN_SIZE_KV,
@@ -363,11 +372,13 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
             VIEW_CONSTANT_KV,
             IS_VIEW_REFERENCED_KV,
             COLUMN_DEF_KV,
-            IS_ROW_TIMESTAMP_KV
+            IS_ROW_TIMESTAMP_KV,
+            ENCODED_COLUMN_QUALIFIER_KV
             );
     static {
         Collections.sort(COLUMN_KV_COLUMNS, KeyValue.COMPARATOR);
     }
+    private static final KeyValue QUALIFIER_COUNTER_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, COLUMN_QUALIFIER_COUNTER_BYTES);
     private static final int DECIMAL_DIGITS_INDEX = COLUMN_KV_COLUMNS.indexOf(DECIMAL_DIGITS_KV);
     private static final int COLUMN_SIZE_INDEX = COLUMN_KV_COLUMNS.indexOf(COLUMN_SIZE_KV);
     private static final int NULLABLE_INDEX = COLUMN_KV_COLUMNS.indexOf(NULLABLE_KV);
@@ -379,9 +390,10 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
     private static final int IS_VIEW_REFERENCED_INDEX = COLUMN_KV_COLUMNS.indexOf(IS_VIEW_REFERENCED_KV);
     private static final int COLUMN_DEF_INDEX = COLUMN_KV_COLUMNS.indexOf(COLUMN_DEF_KV);
     private static final int IS_ROW_TIMESTAMP_INDEX = COLUMN_KV_COLUMNS.indexOf(IS_ROW_TIMESTAMP_KV);
+    private static final int ENCODED_COLUMN_QUALIFIER_INDEX = COLUMN_KV_COLUMNS.indexOf(ENCODED_COLUMN_QUALIFIER_KV);
     
     private static final int LINK_TYPE_INDEX = 0;
-
+    
     private static final KeyValue CLASS_NAME_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, CLASS_NAME_BYTES);
     private static final KeyValue JAR_PATH_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, JAR_PATH_BYTES);
     private static final KeyValue RETURN_TYPE_KV = KeyValue.createFirstOnRow(ByteUtil.EMPTY_BYTE_ARRAY, TABLE_FAMILY_BYTES, RETURN_TYPE_BYTES);
@@ -717,8 +729,12 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                 isRowTimestampKV == null ? false : Boolean.TRUE.equals(PBoolean.INSTANCE.toObject(
                         isRowTimestampKV.getValueArray(), isRowTimestampKV.getValueOffset(),
                         isRowTimestampKV.getValueLength()));
-
-        PColumn column = new PColumnImpl(colName, famName, dataType, maxLength, scale, isNullable, position-1, sortOrder, arraySize, viewConstant, isViewReferenced, expressionStr, isRowTimestamp, false);
+        Cell columnQualifierKV = colKeyValues[ENCODED_COLUMN_QUALIFIER_INDEX];
+        Integer columnQualifier =
+                columnQualifierKV == null ? null : getEncodedColumnQualifier(
+                    columnQualifierKV.getValueArray(), columnQualifierKV.getValueOffset(),
+                    columnQualifierKV.getValueLength());
+        PColumn column = new PColumnImpl(colName, famName, dataType, maxLength, scale, isNullable, position-1, sortOrder, arraySize, viewConstant, isViewReferenced, expressionStr, isRowTimestamp, false, columnQualifier);
         columns.add(column);
     }
     
@@ -926,37 +942,49 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
         boolean isAppendOnlySchema = isAppendOnlySchemaKv == null ? false
                 : Boolean.TRUE.equals(PBoolean.INSTANCE.toObject(isAppendOnlySchemaKv.getValueArray(),
                     isAppendOnlySchemaKv.getValueOffset(), isAppendOnlySchemaKv.getValueLength()));
-        
-        
+        Cell storageSchemeKv = tableKeyValues[STORAGE_SCHEME_INDEX];
+        //TODO: change this once we start having other values for storage schemes
+        StorageScheme storageScheme = storageSchemeKv == null ? StorageScheme.NON_ENCODED_COLUMN_NAMES : StorageScheme
+                .fromSerializedValue((byte)PTinyint.INSTANCE.toObject(storageSchemeKv.getValueArray(),
+                        storageSchemeKv.getValueOffset(), storageSchemeKv.getValueLength()));
+
         List<PColumn> columns = Lists.newArrayListWithExpectedSize(columnCount);
         List<PTable> indexes = Lists.newArrayList();
         List<PName> physicalTables = Lists.newArrayList();
         PName parentTableName = tableType == INDEX ? dataTableName : null;
         PName parentSchemaName = tableType == INDEX ? schemaName : null;
+        EncodedCQCounter cqCounter = (storageScheme == StorageScheme.NON_ENCODED_COLUMN_NAMES || tableType == PTableType.VIEW) ? PTable.EncodedCQCounter.NULL_COUNTER : new EncodedCQCounter();
         while (true) {
-          results.clear();
-          scanner.next(results);
-          if (results.isEmpty()) {
-              break;
-          }
-          Cell colKv = results.get(LINK_TYPE_INDEX);
-          int colKeyLength = colKv.getRowLength();
-          PName colName = newPName(colKv.getRowArray(), colKv.getRowOffset() + offset, colKeyLength-offset);
-          int colKeyOffset = offset + colName.getBytes().length + 1;
-          PName famName = newPName(colKv.getRowArray(), colKv.getRowOffset() + colKeyOffset, colKeyLength-colKeyOffset);
-          if (colName.getString().isEmpty() && famName != null) {
-              LinkType linkType = LinkType.fromSerializedValue(colKv.getValueArray()[colKv.getValueOffset()]);
-              if (linkType == LinkType.INDEX_TABLE) {
-                  addIndexToTable(tenantId, schemaName, famName, tableName, clientTimeStamp, indexes);
-              } else if (linkType == LinkType.PHYSICAL_TABLE) {
-                  physicalTables.add(famName);
-              } else if (linkType == LinkType.PARENT_TABLE) {
-                  parentTableName = PNameFactory.newName(SchemaUtil.getTableNameFromFullName(famName.getBytes()));
-                  parentSchemaName = PNameFactory.newName(SchemaUtil.getSchemaNameFromFullName(famName.getBytes()));
-              }
-          } else {
-              addColumnToTable(results, colName, famName, colKeyValues, columns, saltBucketNum != null);
-          }
+            results.clear();
+            scanner.next(results);
+            if (results.isEmpty()) {
+                break;
+            }
+            Cell colKv = results.get(LINK_TYPE_INDEX);
+            if (colKv != null) {
+                int colKeyLength = colKv.getRowLength();
+                PName colName = newPName(colKv.getRowArray(), colKv.getRowOffset() + offset, colKeyLength-offset);
+                int colKeyOffset = offset + colName.getBytes().length + 1;
+                PName famName = newPName(colKv.getRowArray(), colKv.getRowOffset() + colKeyOffset, colKeyLength-colKeyOffset);
+                if (isQualifierCounterKV(colKv)) {
+                    Integer value = PInteger.INSTANCE.getCodec().decodeInt(colKv.getValueArray(), colKv.getValueOffset(), SortOrder.ASC);
+                    cqCounter.setValue(famName.getString(), value);
+                } else {
+                    if (colName.getString().isEmpty() && famName != null) {
+                        LinkType linkType = LinkType.fromSerializedValue(colKv.getValueArray()[colKv.getValueOffset()]);
+                        if (linkType == LinkType.INDEX_TABLE) {
+                            addIndexToTable(tenantId, schemaName, famName, tableName, clientTimeStamp, indexes);
+                        } else if (linkType == LinkType.PHYSICAL_TABLE) {
+                            physicalTables.add(famName);
+                        } else if (linkType == LinkType.PARENT_TABLE) {
+                            parentTableName = PNameFactory.newName(SchemaUtil.getTableNameFromFullName(famName.getBytes()));
+                            parentSchemaName = PNameFactory.newName(SchemaUtil.getSchemaNameFromFullName(famName.getBytes()));
+                        }
+                    } else {
+                        addColumnToTable(results, colName, famName, colKeyValues, columns, saltBucketNum != null);
+                    }
+                } 
+            }
         }
         // Avoid querying the stats table because we're holding the rowLock here. Issuing an RPC to a remote
         // server while holding this lock is a bad idea and likely to cause contention.
@@ -964,9 +992,17 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                 pkName, saltBucketNum, columns, parentSchemaName, parentTableName, indexes, isImmutableRows, physicalTables, defaultFamilyName,
                 viewStatement, disableWAL, multiTenant, storeNulls, viewType, viewIndexId, indexType,
                 rowKeyOrderOptimizable, transactional, updateCacheFrequency, baseColumnCount,
-                indexDisableTimestamp, isNamespaceMapped, autoPartitionSeq, isAppendOnlySchema);
+                indexDisableTimestamp, isNamespaceMapped, autoPartitionSeq, isAppendOnlySchema, storageScheme, cqCounter);
     }
-
+    
+    private boolean isQualifierCounterKV(Cell kv) {
+        int cmp =
+                Bytes.compareTo(kv.getQualifierArray(), kv.getQualifierOffset(),
+                    kv.getQualifierLength(), QUALIFIER_COUNTER_KV.getQualifierArray(),
+                    QUALIFIER_COUNTER_KV.getQualifierOffset(), QUALIFIER_COUNTER_KV.getQualifierLength());
+        return cmp == 0;
+    }
+    
     private PSchema getSchema(RegionScanner scanner, long clientTimeStamp) throws IOException, SQLException {
         List<Cell> results = Lists.newArrayList();
         scanner.next(results);
@@ -1486,46 +1522,46 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                 Short indexId = null;
                 if (request.hasAllocateIndexId() && request.getAllocateIndexId()) {
                     String tenantIdStr = tenantIdBytes.length == 0 ? null : Bytes.toString(tenantIdBytes);
-                    try (PhoenixConnection connection = QueryUtil.getConnectionOnServer(env.getConfiguration()).unwrap(PhoenixConnection.class)){
-                    PName physicalName = parentTable.getPhysicalName();
-                    int nSequenceSaltBuckets = connection.getQueryServices().getSequenceSaltBuckets();
-                    SequenceKey key = MetaDataUtil.getViewIndexSequenceKey(tenantIdStr, physicalName,
+                    try (PhoenixConnection connection = QueryUtil.getConnectionOnServer(env.getConfiguration()).unwrap(PhoenixConnection.class)) {
+                        PName physicalName = parentTable.getPhysicalName();
+                        int nSequenceSaltBuckets = connection.getQueryServices().getSequenceSaltBuckets();
+                        SequenceKey key = MetaDataUtil.getViewIndexSequenceKey(tenantIdStr, physicalName,
                             nSequenceSaltBuckets, parentTable.isNamespaceMapped() );
                         // TODO Review Earlier sequence was created at (SCN-1/LATEST_TIMESTAMP) and incremented at the client max(SCN,dataTable.getTimestamp), but it seems we should
                         // use always LATEST_TIMESTAMP to avoid seeing wrong sequence values by different connection having SCN
                         // or not. 
-                    long sequenceTimestamp = HConstants.LATEST_TIMESTAMP;
-                    try {
-                        connection.getQueryServices().createSequence(key.getTenantId(), key.getSchemaName(), key.getSequenceName(),
+                        long sequenceTimestamp = HConstants.LATEST_TIMESTAMP;
+                        try {
+                            connection.getQueryServices().createSequence(key.getTenantId(), key.getSchemaName(), key.getSequenceName(),
                                 Short.MIN_VALUE, 1, 1, Long.MIN_VALUE, Long.MAX_VALUE, false, sequenceTimestamp);
-                    } catch (SequenceAlreadyExistsException e) {
-                    }
-                    long[] seqValues = new long[1];
-                    SQLException[] sqlExceptions = new SQLException[1];
-                    connection.getQueryServices().incrementSequences(Collections.singletonList(new SequenceAllocation(key, 1)),
+                        } catch (SequenceAlreadyExistsException e) {
+                        }
+                        long[] seqValues = new long[1];
+                        SQLException[] sqlExceptions = new SQLException[1];
+                        connection.getQueryServices().incrementSequences(Collections.singletonList(new SequenceAllocation(key, 1)),
                             HConstants.LATEST_TIMESTAMP, seqValues, sqlExceptions);
-                    if (sqlExceptions[0] != null) {
-                        throw sqlExceptions[0];
-                    }
-                    long seqValue = seqValues[0];
-                    if (seqValue > Short.MAX_VALUE) {
-                        builder.setReturnCode(MetaDataProtos.MutationCode.TOO_MANY_INDEXES);
-                        builder.setMutationTime(EnvironmentEdgeManager.currentTimeMillis());
-                        done.run(builder.build());
-                        return;
-                    }
-                    Put tableHeaderPut = MetaDataUtil.getPutOnlyTableHeaderRow(tableMetadata);
-                    NavigableMap<byte[], List<Cell>> familyCellMap = tableHeaderPut.getFamilyCellMap();
-                    List<Cell> cells = familyCellMap.get(TABLE_FAMILY_BYTES);
-                    Cell cell = cells.get(0);
-                    PDataType dataType = MetaDataUtil.getViewIndexIdDataType();
-                    Object val = dataType.toObject(seqValue, PLong.INSTANCE);
-                    byte[] bytes = new byte [dataType.getByteSize() + 1];
-                    dataType.toBytes(val, bytes, 0);
-                    Cell indexIdCell = new KeyValue(cell.getRow(), cell.getFamily(), VIEW_INDEX_ID_BYTES,
+                        if (sqlExceptions[0] != null) {
+                            throw sqlExceptions[0];
+                        }
+                        long seqValue = seqValues[0];
+                        if (seqValue > Short.MAX_VALUE) {
+                            builder.setReturnCode(MetaDataProtos.MutationCode.TOO_MANY_INDEXES);
+                            builder.setMutationTime(EnvironmentEdgeManager.currentTimeMillis());
+                            done.run(builder.build());
+                            return;
+                        }
+                        Put tableHeaderPut = MetaDataUtil.getPutOnlyTableHeaderRow(tableMetadata);
+                        NavigableMap<byte[], List<Cell>> familyCellMap = tableHeaderPut.getFamilyCellMap();
+                        List<Cell> cells = familyCellMap.get(TABLE_FAMILY_BYTES);
+                        Cell cell = cells.get(0);
+                        PDataType dataType = MetaDataUtil.getViewIndexIdDataType();
+                        Object val = dataType.toObject(seqValue, PLong.INSTANCE);
+                        byte[] bytes = new byte [dataType.getByteSize() + 1];
+                        dataType.toBytes(val, bytes, 0);
+                        Cell indexIdCell = new KeyValue(cell.getRow(), cell.getFamily(), VIEW_INDEX_ID_BYTES,
                             cell.getTimestamp(), Type.codeToType(cell.getTypeByte()), bytes);
-                    cells.add(indexIdCell);
-                    indexId = (short) seqValue;
+                        cells.add(indexIdCell);
+                        indexId = (short) seqValue;
                     }
                 }
                 
@@ -1536,7 +1572,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                 // indexing on the system table. This is an issue because of the way we manage batch mutation
                 // in the Indexer.
                 region.mutateRowsWithLocks(tableMetadata, Collections.<byte[]> emptySet());
-
+                
                 // Invalidate the cache - the next getTable call will add it
                 // TODO: consider loading the table that was just created here, patching up the parent table, and updating the cache
                 Cache<ImmutableBytesPtr,PMetaDataEntity> metaDataCache = GlobalCache.getInstance(this.env).getMetaDataCache();
@@ -1988,7 +2024,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                     return result;
                 }
                 region.mutateRowsWithLocks(tableMetadata, Collections.<byte[]> emptySet());
-                // Invalidate from cache
+                // Invalidate from cache.
                 for (ImmutableBytesPtr invalidateKey : invalidateList) {
                     metaDataCache.invalidate(invalidateKey);
                 }
@@ -2161,6 +2197,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                 byte[][] rkmd = new byte[5][];
                 int pkCount = getVarChars(m.getRow(), rkmd);
                 if (pkCount > COLUMN_NAME_INDEX
+                        && rkmd[COLUMN_NAME_INDEX] != null && rkmd[COLUMN_NAME_INDEX].length > 0
                         && Bytes.compareTo(schemaName, rkmd[SCHEMA_NAME_INDEX]) == 0
                         && Bytes.compareTo(tableName, rkmd[TABLE_NAME_INDEX]) == 0) {
                     columnPutsForBaseTable.add(new PutWithOrdinalPosition((Put)m, getInteger((Put)m, TABLE_FAMILY_BYTES, ORDINAL_POSITION_BYTES)));
@@ -2195,8 +2232,8 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                 String columnName = Bytes.toString(rkmd[COLUMN_NAME_INDEX]);
                 String columnFamily = rkmd[FAMILY_NAME_INDEX] == null ? null : Bytes.toString(rkmd[FAMILY_NAME_INDEX]);
                 try {
-                    existingViewColumn = columnFamily == null ? view.getColumn(columnName) : view.getColumnFamily(
-                            columnFamily).getColumn(columnName);
+                    existingViewColumn = columnFamily == null ? view.getPColumnForColumnName(columnName) : view.getColumnFamily(
+                            columnFamily).getPColumnForColumnName(columnName);
                 } catch (ColumnFamilyNotFoundException e) {
                     // ignore since it means that the column family is not present for the column to be added.
                 } catch (ColumnNotFoundException e) {
@@ -2323,26 +2360,26 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                     columnsAddedToBaseTable++;
                 }
             }
-            /*
-             * Allow adding a pk columns to base table : 1. if all the view pk columns are exactly the same as the base
-             * table pk columns 2. if we are adding all the existing view pk columns to the base table
-             */ 
-            if (addingExistingPkCol && !viewPkCols.equals(basePhysicalTable.getPKColumns())) {
-                return new MetaDataMutationResult(MutationCode.UNALLOWED_TABLE_MUTATION, EnvironmentEdgeManager.currentTimeMillis(), basePhysicalTable);
-            }
-            addViewIndexesHeaderRowMutations(mutationsForAddingColumnsToViews, invalidateList, clientTimeStamp, view,
-                    deltaNumPkColsSoFar);
-            
-            /*
-             * Increment the sequence number by 1 if:
-             * 1) For a diverged view, there were columns (pk columns) added to the view.
-             * 2) For a non-diverged view if the base column count changed.
-             */
-            boolean changeSequenceNumber = (isDivergedView(view) && columnsAddedToView > 0)
-                    || (!isDivergedView(view) && columnsAddedToBaseTable > 0);
-            updateViewHeaderRow(basePhysicalTable, tableMetadata, mutationsForAddingColumnsToViews,
-                invalidateList, clientTimeStamp, columnsAddedToView, columnsAddedToBaseTable,
-                viewKey, view, ordinalPositionList, numCols, changeSequenceNumber);
+           /*
+            * Allow adding a pk columns to base table : 1. if all the view pk columns are exactly the same as the base
+            * table pk columns 2. if we are adding all the existing view pk columns to the base table
+            */ 
+           if (addingExistingPkCol && !viewPkCols.equals(basePhysicalTable.getPKColumns())) {
+               return new MetaDataMutationResult(MutationCode.UNALLOWED_TABLE_MUTATION, EnvironmentEdgeManager.currentTimeMillis(), basePhysicalTable);
+           }
+           addViewIndexesHeaderRowMutations(mutationsForAddingColumnsToViews, invalidateList, clientTimeStamp, view,
+                   deltaNumPkColsSoFar);
+           
+           /*
+            * Increment the sequence number by 1 if:
+            * 1) For a diverged view, there were columns (pk columns) added to the view.
+            * 2) For a non-diverged view if the base column count changed.
+            */
+           boolean changeSequenceNumber = (isDivergedView(view) && columnsAddedToView > 0)
+                   || (!isDivergedView(view) && columnsAddedToBaseTable > 0);
+           updateViewHeaderRow(basePhysicalTable, tableMetadata, mutationsForAddingColumnsToViews,
+               invalidateList, clientTimeStamp, columnsAddedToView, columnsAddedToBaseTable,
+               viewKey, view, ordinalPositionList, numCols, changeSequenceNumber);
         }
         return null;
     }
@@ -2500,8 +2537,8 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                 byte[] columnKey = getColumnKey(viewKey, columnName, columnFamily);
                 try {
                     existingViewColumn =
-                            columnFamily == null ? view.getColumn(columnName) : view
-                                    .getColumnFamily(columnFamily).getColumn(columnName);
+                            columnFamily == null ? view.getPColumnForColumnName(columnName) : view
+                                    .getColumnFamily(columnFamily).getPColumnForColumnName(columnName);
                 } catch (ColumnFamilyNotFoundException e) {
                     // ignore since it means that the column family is not present for the column to
                     // be added.
@@ -2567,7 +2604,25 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
     
     private MetaDataMutationResult validateColumnForAddToBaseTable(PColumn existingViewColumn, Put columnToBeAdded, PTable basePhysicalTable, boolean isColumnToBeAddPkCol, PTable view) {
         if (existingViewColumn != null) {
-            
+            if (EncodedColumnsUtil.usesEncodedColumnNames(basePhysicalTable) && !SchemaUtil.isPKColumn(existingViewColumn)) {
+                /*
+                 * If the column already exists in a view, then we cannot add the column to the base
+                 * table. The reason is subtle and is as follows: consider the case where a table
+                 * has two views where both the views have the same key value column KV. Now, we
+                 * dole out encoded column qualifiers for key value columns in views by using the
+                 * counters stored in the base physical table. So the KV column can have different
+                 * column qualifiers for the two views. For example, 11 for VIEW1 and 12 for VIEW2.
+                 * This naturally extends to rows being inserted using the two views having
+                 * different column qualifiers for the column named KV. Now, when an attempt is made
+                 * to add column KV to the base table, we cannot decide which column qualifier
+                 * should that column be assigned. It cannot be a number different than 11 or 12
+                 * since a query like SELECT KV FROM BASETABLE would return null for KV which is
+                 * incorrect since column KV is present in rows inserted from the two views. We
+                 * cannot use 11 or 12 either because we will then incorrectly return value of KV
+                 * column inserted using only one view.
+                 */
+                return new MetaDataMutationResult(MutationCode.UNALLOWED_TABLE_MUTATION, EnvironmentEdgeManager.currentTimeMillis(), basePhysicalTable);
+            }
             // Validate data type is same
             int baseColumnDataType = getInteger(columnToBeAdded, TABLE_FAMILY_BYTES, DATA_TYPE_BYTES);
             if (baseColumnDataType != existingViewColumn.getDataType().getSqlType()) {
@@ -2797,6 +2852,16 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                                 	return mutationResult;
                             } 
                         }
+                    } else if (type == PTableType.VIEW
+                            && EncodedColumnsUtil.usesEncodedColumnNames(table)) {
+                        /*
+                         * When adding a column to a view that uses encoded column name scheme, we
+                         * need to modify the CQ counters stored in the view's physical table. So to
+                         * make sure clients get the latest PTable, we need to invalidate the cache
+                         * entry.
+                         */
+                        invalidateList.add(new ImmutableBytesPtr(MetaDataUtil
+                                .getPhysicalTableRowForView(table)));
                     }
                     for (Mutation m : tableMetaData) {
                         byte[] key = m.getRow();
@@ -2810,7 +2875,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                                         && rowKeyMetaData[PhoenixDatabaseMetaData.FAMILY_NAME_INDEX].length > 0) {
                                     PColumnFamily family =
                                             table.getColumnFamily(rowKeyMetaData[PhoenixDatabaseMetaData.FAMILY_NAME_INDEX]);
-                                    family.getColumn(rowKeyMetaData[PhoenixDatabaseMetaData.COLUMN_NAME_INDEX]);
+                                    family.getPColumnForColumnNameBytes(rowKeyMetaData[PhoenixDatabaseMetaData.COLUMN_NAME_INDEX]);
                                 } else if (pkCount > COLUMN_NAME_INDEX
                                         && rowKeyMetaData[PhoenixDatabaseMetaData.COLUMN_NAME_INDEX].length > 0) {
                                     addingPKColumn = true;
@@ -3063,7 +3128,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                                         PColumnFamily family =
                                                 table.getColumnFamily(rowKeyMetaData[PhoenixDatabaseMetaData.FAMILY_NAME_INDEX]);
                                         columnToDelete =
-                                                family.getColumn(rowKeyMetaData[PhoenixDatabaseMetaData.COLUMN_NAME_INDEX]);
+                                                family.getPColumnForColumnNameBytes(rowKeyMetaData[PhoenixDatabaseMetaData.COLUMN_NAME_INDEX]);
                                     } else if (pkCount > COLUMN_NAME_INDEX
                                             && rowKeyMetaData[PhoenixDatabaseMetaData.COLUMN_NAME_INDEX].length > 0) {
                                         deletePKColumn = true;
@@ -3152,10 +3217,11 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
             byte[] indexKey =
                     SchemaUtil.getTableKey(tenantId, index.getSchemaName().getBytes(), index
                             .getTableName().getBytes());
+            Pair<String, String> columnToDeleteInfo = new Pair<>(columnToDelete.getFamilyName().getString(), columnToDelete.getName().getString());
+            boolean isColumnIndexed = indexMaintainer.getIndexedColumnInfo().contains(columnToDeleteInfo);
+            boolean isCoveredColumn = indexMaintainer.getCoveredColumnInfo().contains(columnToDeleteInfo);
             // If index requires this column for its pk, then drop it
-            if (indexMaintainer.getIndexedColumns().contains(
-                new ColumnReference(columnToDelete.getFamilyName().getBytes(), columnToDelete
-                        .getName().getBytes()))) {
+            if (isColumnIndexed) {
                 // Since we're dropping the index, lock it to ensure
                 // that a change in index state doesn't
                 // occur while we're dropping it.
@@ -3176,9 +3242,7 @@ public class MetaDataEndpointImpl extends MetaDataProtocol implements Coprocesso
                 invalidateList.add(new ImmutableBytesPtr(indexKey));
             }
             // If the dropped column is a covered index column, invalidate the index
-            else if (indexMaintainer.getCoveredColumns().contains(
-                new ColumnReference(columnToDelete.getFamilyName().getBytes(), columnToDelete
-                        .getName().getBytes()))) {
+            else if (isCoveredColumn){
                 invalidateList.add(new ImmutableBytesPtr(indexKey));
             }
         }

http://git-wip-us.apache.org/repos/asf/phoenix/blob/ede568e9/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/ScanRegionObserver.java
----------------------------------------------------------------------
diff --git a/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/ScanRegionObserver.java b/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/ScanRegionObserver.java
index 3cfe790..8a833ac 100644
--- a/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/ScanRegionObserver.java
+++ b/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/ScanRegionObserver.java
@@ -107,7 +107,7 @@ public class ScanRegionObserver extends BaseScannerRegionObserver {
         }
     }
 
-    public static OrderedResultIterator deserializeFromScan(Scan scan, RegionScanner s) {
+    private static OrderedResultIterator deserializeFromScan(Scan scan, RegionScanner s) {
         byte[] topN = scan.getAttribute(BaseScannerRegionObserver.TOPN);
         if (topN == null) {
             return null;
@@ -125,7 +125,7 @@ public class ScanRegionObserver extends BaseScannerRegionObserver {
                 orderByExpression.readFields(input);
                 orderByExpressions.add(orderByExpression);
             }
-            ResultIterator inner = new RegionScannerResultIterator(s);
+            ResultIterator inner = new RegionScannerResultIterator(s, ScanUtil.getMinMaxQualifiersFromScan(scan));
             return new OrderedResultIterator(inner, orderByExpressions, thresholdBytes, limit >= 0 ? limit : null, null,
                     estimatedRowSize);
         } catch (IOException e) {
@@ -218,21 +218,24 @@ public class ScanRegionObserver extends BaseScannerRegionObserver {
         
         final TupleProjector p = TupleProjector.deserializeProjectorFromScan(scan);
         final HashJoinInfo j = HashJoinInfo.deserializeHashJoinFromScan(scan);
+        //TODO: samarth make this a client side check by looking at order by and group by expressions. Then use that to set min max qualifiers. We can then make useQualifierListAsIndex
+        // a member variable of BaseScannerRegionObserver.
+        boolean useQualifierAsIndex = ScanUtil.useQualifierAsIndex(ScanUtil.getMinMaxQualifiersFromScan(scan)) && scan.getAttribute(BaseScannerRegionObserver.TOPN) != null;
         innerScanner =
                 getWrappedScanner(c, innerScanner, arrayKVRefs, arrayFuncRefs, offset, scan,
                     dataColumns, tupleProjector, dataRegion, indexMaintainer, tx,
-                    viewConstants, kvSchema, kvSchemaBitSet, j == null ? p : null, ptr);
+                    viewConstants, kvSchema, kvSchemaBitSet, j == null ? p : null, ptr, useQualifierAsIndex);
 
         final ImmutableBytesPtr tenantId = ScanUtil.getTenantId(scan);
         if (j != null) {
-            innerScanner = new HashJoinRegionScanner(innerScanner, p, j, tenantId, c.getEnvironment());
+            innerScanner = new HashJoinRegionScanner(innerScanner, p, j, tenantId, c.getEnvironment(), useQualifierAsIndex);
         }
         if (scanOffset != null) {
             innerScanner = getOffsetScanner(c, innerScanner,
-                    new OffsetResultIterator(new RegionScannerResultIterator(innerScanner), scanOffset),
+                    new OffsetResultIterator(new RegionScannerResultIterator(innerScanner, ScanUtil.getMinMaxQualifiersFromScan(scan)), scanOffset),
                     scan.getAttribute(QueryConstants.LAST_SCAN) != null);
         }
-        final OrderedResultIterator iterator = deserializeFromScan(scan,innerScanner);
+        final OrderedResultIterator iterator = deserializeFromScan(scan, innerScanner);
         if (iterator == null) {
             return innerScanner;
         }

http://git-wip-us.apache.org/repos/asf/phoenix/blob/ede568e9/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/UngroupedAggregateRegionObserver.java
----------------------------------------------------------------------
diff --git a/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/UngroupedAggregateRegionObserver.java b/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/UngroupedAggregateRegionObserver.java
index 0d0f0c2..a313dd1 100644
--- a/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/UngroupedAggregateRegionObserver.java
+++ b/phoenix-core/src/main/java/org/apache/phoenix/coprocessor/UngroupedAggregateRegionObserver.java
@@ -24,6 +24,7 @@ import static org.apache.phoenix.query.QueryConstants.UNGROUPED_AGG_ROW_KEY;
 import static org.apache.phoenix.query.QueryServices.MUTATE_BATCH_SIZE_ATTRIB;
 import static org.apache.phoenix.schema.stats.StatisticsCollectionRunTracker.COMPACTION_UPDATE_STATS_ROW_COUNT;
 import static org.apache.phoenix.schema.stats.StatisticsCollectionRunTracker.CONCURRENT_UPDATE_STATS_ROW_COUNT;
+import static org.apache.phoenix.util.ScanUtil.getMinMaxQualifiersFromScan;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -96,7 +97,10 @@ import org.apache.phoenix.schema.ValueSchema.Field;
 import org.apache.phoenix.schema.stats.StatisticsCollectionRunTracker;
 import org.apache.phoenix.schema.stats.StatisticsCollector;
 import org.apache.phoenix.schema.stats.StatisticsCollectorFactory;
+import org.apache.phoenix.schema.tuple.EncodedColumnQualiferCellsList;
 import org.apache.phoenix.schema.tuple.MultiKeyValueTuple;
+import org.apache.phoenix.schema.tuple.PositionBasedMultiKeyValueTuple;
+import org.apache.phoenix.schema.tuple.Tuple;
 import org.apache.phoenix.schema.types.PBinary;
 import org.apache.phoenix.schema.types.PChar;
 import org.apache.phoenix.schema.types.PDataType;
@@ -305,6 +309,7 @@ public class UngroupedAggregateRegionObserver extends BaseScannerRegionObserver
         byte[] deleteCQ = null;
         byte[] deleteCF = null;
         byte[] emptyCF = null;
+        byte[] emptyKVQualifier = null;
         ImmutableBytesWritable ptr = new ImmutableBytesWritable();
         if (upsertSelectTable != null) {
             isUpsert = true;
@@ -320,12 +325,14 @@ public class UngroupedAggregateRegionObserver extends BaseScannerRegionObserver
                 deleteCQ = scan.getAttribute(BaseScannerRegionObserver.DELETE_CQ);
             }
             emptyCF = scan.getAttribute(BaseScannerRegionObserver.EMPTY_CF);
+            emptyKVQualifier = scan.getAttribute(BaseScannerRegionObserver.EMPTY_COLUMN_QUALIFIER);
         }
         TupleProjector tupleProjector = null;
         byte[][] viewConstants = null;
         ColumnReference[] dataColumns = IndexUtil.deserializeDataTableColumnsToJoin(scan);
         final TupleProjector p = TupleProjector.deserializeProjectorFromScan(scan);
         final HashJoinInfo j = HashJoinInfo.deserializeHashJoinFromScan(scan);
+        boolean useQualifierAsIndex = ScanUtil.useQualifierAsIndex(ScanUtil.getMinMaxQualifiersFromScan(scan)) && scan.getAttribute(BaseScannerRegionObserver.TOPN) != null;
         if ((localIndexScan && !isDelete && !isDescRowKeyOrderUpgrade) || (j == null && p != null)) {
             if (dataColumns != null) {
                 tupleProjector = IndexUtil.getTupleProjector(scan, dataColumns);
@@ -334,11 +341,11 @@ public class UngroupedAggregateRegionObserver extends BaseScannerRegionObserver
             ImmutableBytesWritable tempPtr = new ImmutableBytesWritable();
             theScanner =
                     getWrappedScanner(c, theScanner, offset, scan, dataColumns, tupleProjector, 
-                            c.getEnvironment().getRegion(), indexMaintainers == null ? null : indexMaintainers.get(0), viewConstants, p, tempPtr);
+                            c.getEnvironment().getRegion(), indexMaintainers == null ? null : indexMaintainers.get(0), viewConstants, p, tempPtr, useQualifierAsIndex);
         } 
         
         if (j != null)  {
-            theScanner = new HashJoinRegionScanner(theScanner, p, j, ScanUtil.getTenantId(scan), env);
+            theScanner = new HashJoinRegionScanner(theScanner, p, j, ScanUtil.getTenantId(scan), env, useQualifierAsIndex);
         }
         
         int batchSize = 0;
@@ -374,7 +381,8 @@ public class UngroupedAggregateRegionObserver extends BaseScannerRegionObserver
         Aggregator[] rowAggregators = aggregators.getAggregators();
         boolean hasMore;
         boolean hasAny = false;
-        MultiKeyValueTuple result = new MultiKeyValueTuple();
+        Pair<Integer, Integer> minMaxQualifiers = getMinMaxQualifiersFromScan(scan);
+        Tuple result = useQualifierAsIndex ? new PositionBasedMultiKeyValueTuple() : new MultiKeyValueTuple();
         if (logger.isDebugEnabled()) {
             logger.debug(LogUtil.addCustomAnnotations("Starting ungrouped coprocessor scan " + scan + " "+region.getRegionInfo(), ScanUtil.getCustomAnnotations(scan)));
         }
@@ -392,7 +400,7 @@ public class UngroupedAggregateRegionObserver extends BaseScannerRegionObserver
             acquiredLock = true;
             synchronized (innerScanner) {
                 do {
-                    List<Cell> results = new ArrayList<Cell>();
+                    List<Cell> results = useQualifierAsIndex ? new EncodedColumnQualiferCellsList(minMaxQualifiers.getFirst(), minMaxQualifiers.getSecond()) : new ArrayList<Cell>();
                     // Results are potentially returned even when the return value of s.next is false
                     // since this is an indication of whether or not there are more values after the
                     // ones returned