diff --git a/fe/src/com/baidu/palo/clone/CloneChecker.java b/fe/src/com/baidu/palo/clone/CloneChecker.java
index 88e7dc95c54471..fcc2d51cbb2955 100644
--- a/fe/src/com/baidu/palo/clone/CloneChecker.java
+++ b/fe/src/com/baidu/palo/clone/CloneChecker.java
@@ -481,10 +481,7 @@ private Map<Level, Set<List<Long>>> initBackendCapacityInfos(Map<Long, BackendIn
             }
         }
 
-        if (backendInfosMap.size() <= 1) {
-            return null;
-        }
-
+        // maybe backendInfosMap size == 1 when migrate db
         // calculate avg used ratio
         long totalCapacityB = 0;
         long availableCapacityB = 0;
@@ -564,10 +561,7 @@ private Map<Level, Set<List<Long>>> initBackendDistributionInfos(Map<Long, Backe
             }
         }
 
-        if (backendInfosMap.size() <= 1) {
-            return null;
-        }
-
+        // maybe backendInfosMap size == 1 when migrate db
         // init distributionLevelToBackendIds
         Map<Level, Set<List<Long>>> distributionLevelToBackendIds = new HashMap<Level, Set<List<Long>>>();
         for (Level level : Level.values()) {
diff --git a/gensrc/parser/sql_scanner.flex b/gensrc/parser/sql_scanner.flex
index bf86863f4e8d96..21dcf3fd1635b2 100644
--- a/gensrc/parser/sql_scanner.flex
+++ b/gensrc/parser/sql_scanner.flex
@@ -73,6 +73,7 @@ import com.baidu.palo.common.util.SqlUtils;
         keywordMap.put("asc", new Integer(SqlParserSymbols.KW_ASC));
         keywordMap.put("authors", new Integer(SqlParserSymbols.KW_AUTHORS));
         keywordMap.put("backend", new Integer(SqlParserSymbols.KW_BACKEND));
+        keywordMap.put("backends", new Integer(SqlParserSymbols.KW_BACKENDS));
         keywordMap.put("backup", new Integer(SqlParserSymbols.KW_BACKUP));
         keywordMap.put("begin", new Integer(SqlParserSymbols.KW_BEGIN));
         keywordMap.put("between", new Integer(SqlParserSymbols.KW_BETWEEN));