HBASE-13938 Deletes done during the region merge transaction may get eclipsed (ddas, enis, ndimiduk)

hbase-client/src/main/java/org/apache/hadoop/hbase/MetaTableAccessor.java

@@ -945,10 +945,18 @@ public class MetaTableAccessor {
    * table
    */
   public static Delete makeDeleteFromRegionInfo(HRegionInfo regionInfo) {
+    return makeDeleteFromRegionInfo(regionInfo, HConstants.LATEST_TIMESTAMP);
+  }
+
+  /**
+   * Generates and returns a Delete containing the region info for the catalog
+   * table
+   */
+  public static Delete makeDeleteFromRegionInfo(HRegionInfo regionInfo, long ts) {
     if (regionInfo == null) {
       throw new IllegalArgumentException("Can't make a delete for null region");
     }
-    Delete delete = new Delete(regionInfo.getRegionName());
+    Delete delete = new Delete(regionInfo.getRegionName(), ts);
     return delete;
   }
 
@@ -1217,25 +1225,30 @@ public class MetaTableAccessor {
    * @param regionA
    * @param regionB
    * @param sn the location of the region
+   * @param masterSystemTime
    * @throws IOException
    */
   public static void mergeRegions(final Connection connection, HRegionInfo mergedRegion,
-      HRegionInfo regionA, HRegionInfo regionB, ServerName sn, int regionReplication)
+      HRegionInfo regionA, HRegionInfo regionB, ServerName sn, int regionReplication,
+      long masterSystemTime)
           throws IOException {
     Table meta = getMetaHTable(connection);
     try {
       HRegionInfo copyOfMerged = new HRegionInfo(mergedRegion);
 
+      // use the maximum of what master passed us vs local time.
+      long time = Math.max(EnvironmentEdgeManager.currentTime(), masterSystemTime);
+
       // Put for parent
-      Put putOfMerged = makePutFromRegionInfo(copyOfMerged);
+      Put putOfMerged = makePutFromRegionInfo(copyOfMerged, time);
       putOfMerged.addImmutable(HConstants.CATALOG_FAMILY, HConstants.MERGEA_QUALIFIER,
         regionA.toByteArray());
       putOfMerged.addImmutable(HConstants.CATALOG_FAMILY, HConstants.MERGEB_QUALIFIER,
         regionB.toByteArray());
 
       // Deletes for merging regions
-      Delete deleteA = makeDeleteFromRegionInfo(regionA);
+      Delete deleteA = makeDeleteFromRegionInfo(regionA, time);
-      Delete deleteB = makeDeleteFromRegionInfo(regionB);
+      Delete deleteB = makeDeleteFromRegionInfo(regionB, time);
 
       // The merged is a new region, openSeqNum = 1 is fine.
       addLocation(putOfMerged, sn, 1, -1, mergedRegion.getReplicaId());

hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/RequestConverter.java

@@ -945,6 +945,8 @@ public final class RequestConverter {
     builder.setRegionA(regionASpecifier);
     builder.setRegionB(regionBSpecifier);
     builder.setForcible(forcible);
+    // send the master's wall clock time as well, so that the RS can refer to it
+    builder.setMasterSystemTime(EnvironmentEdgeManager.currentTime());
     return builder.build();
   }
 

hbase-protocol/src/main/java/org/apache/hadoop/hbase/protobuf/generated/AdminProtos.java

@@ -14642,6 +14642,24 @@ public final class AdminProtos {
      * <code>optional bool forcible = 3 [default = false];</code>
      */
     boolean getForcible();
+
+    // optional uint64 master_system_time = 4;
+    /**
+     * <code>optional uint64 master_system_time = 4;</code>
+     *
+     * <pre>
+     * wall clock time from master
+     * </pre>
+     */
+    boolean hasMasterSystemTime();
+    /**
+     * <code>optional uint64 master_system_time = 4;</code>
+     *
+     * <pre>
+     * wall clock time from master
+     * </pre>
+     */
+    long getMasterSystemTime();
   }
   /**
    * Protobuf type {@code MergeRegionsRequest}
@@ -14732,6 +14750,11 @@ public final class AdminProtos {
               forcible_ = input.readBool();
               break;
             }
+            case 32: {
+              bitField0_ |= 0x00000008;
+              masterSystemTime_ = input.readUInt64();
+              break;
+            }
           }
         }
       } catch (com.google.protobuf.InvalidProtocolBufferException e) {
@@ -14832,10 +14855,35 @@ public final class AdminProtos {
       return forcible_;
     }
 
+    // optional uint64 master_system_time = 4;
+    public static final int MASTER_SYSTEM_TIME_FIELD_NUMBER = 4;
+    private long masterSystemTime_;
+    /**
+     * <code>optional uint64 master_system_time = 4;</code>
+     *
+     * <pre>
+     * wall clock time from master
+     * </pre>
+     */
+    public boolean hasMasterSystemTime() {
+      return ((bitField0_ & 0x00000008) == 0x00000008);
+    }
+    /**
+     * <code>optional uint64 master_system_time = 4;</code>
+     *
+     * <pre>
+     * wall clock time from master
+     * </pre>
+     */
+    public long getMasterSystemTime() {
+      return masterSystemTime_;
+    }
+
     private void initFields() {
       regionA_ = org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.RegionSpecifier.getDefaultInstance();
       regionB_ = org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.RegionSpecifier.getDefaultInstance();
       forcible_ = false;
+      masterSystemTime_ = 0L;
     }
     private byte memoizedIsInitialized = -1;
     public final boolean isInitialized() {
@@ -14874,6 +14922,9 @@ public final class AdminProtos {
       if (((bitField0_ & 0x00000004) == 0x00000004)) {
         output.writeBool(3, forcible_);
       }
+      if (((bitField0_ & 0x00000008) == 0x00000008)) {
+        output.writeUInt64(4, masterSystemTime_);
+      }
       getUnknownFields().writeTo(output);
     }
 
@@ -14895,6 +14946,10 @@ public final class AdminProtos {
         size += com.google.protobuf.CodedOutputStream
           .computeBoolSize(3, forcible_);
       }
+      if (((bitField0_ & 0x00000008) == 0x00000008)) {
+        size += com.google.protobuf.CodedOutputStream
+          .computeUInt64Size(4, masterSystemTime_);
+      }
       size += getUnknownFields().getSerializedSize();
       memoizedSerializedSize = size;
       return size;
@@ -14933,6 +14988,11 @@ public final class AdminProtos {
         result = result && (getForcible()
             == other.getForcible());
       }
+      result = result && (hasMasterSystemTime() == other.hasMasterSystemTime());
+      if (hasMasterSystemTime()) {
+        result = result && (getMasterSystemTime()
+            == other.getMasterSystemTime());
+      }
       result = result &&
           getUnknownFields().equals(other.getUnknownFields());
       return result;
@@ -14958,6 +15018,10 @@ public final class AdminProtos {
         hash = (37 * hash) + FORCIBLE_FIELD_NUMBER;
         hash = (53 * hash) + hashBoolean(getForcible());
       }
+      if (hasMasterSystemTime()) {
+        hash = (37 * hash) + MASTER_SYSTEM_TIME_FIELD_NUMBER;
+        hash = (53 * hash) + hashLong(getMasterSystemTime());
+      }
       hash = (29 * hash) + getUnknownFields().hashCode();
       memoizedHashCode = hash;
       return hash;
@@ -15090,6 +15154,8 @@ public final class AdminProtos {
         bitField0_ = (bitField0_ & ~0x00000002);
         forcible_ = false;
         bitField0_ = (bitField0_ & ~0x00000004);
+        masterSystemTime_ = 0L;
+        bitField0_ = (bitField0_ & ~0x00000008);
         return this;
       }
 
@@ -15138,6 +15204,10 @@ public final class AdminProtos {
           to_bitField0_ |= 0x00000004;
         }
         result.forcible_ = forcible_;
+        if (((from_bitField0_ & 0x00000008) == 0x00000008)) {
+          to_bitField0_ |= 0x00000008;
+        }
+        result.masterSystemTime_ = masterSystemTime_;
         result.bitField0_ = to_bitField0_;
         onBuilt();
         return result;
@@ -15163,6 +15233,9 @@ public final class AdminProtos {
         if (other.hasForcible()) {
           setForcible(other.getForcible());
         }
+        if (other.hasMasterSystemTime()) {
+          setMasterSystemTime(other.getMasterSystemTime());
+        }
         this.mergeUnknownFields(other.getUnknownFields());
         return this;
       }
@@ -15473,6 +15546,55 @@ public final class AdminProtos {
         return this;
       }
 
+      // optional uint64 master_system_time = 4;
+      private long masterSystemTime_ ;
+      /**
+       * <code>optional uint64 master_system_time = 4;</code>
+       *
+       * <pre>
+       * wall clock time from master
+       * </pre>
+       */
+      public boolean hasMasterSystemTime() {
+        return ((bitField0_ & 0x00000008) == 0x00000008);
+      }
+      /**
+       * <code>optional uint64 master_system_time = 4;</code>
+       *
+       * <pre>
+       * wall clock time from master
+       * </pre>
+       */
+      public long getMasterSystemTime() {
+        return masterSystemTime_;
+      }
+      /**
+       * <code>optional uint64 master_system_time = 4;</code>
+       *
+       * <pre>
+       * wall clock time from master
+       * </pre>
+       */
+      public Builder setMasterSystemTime(long value) {
+        bitField0_ |= 0x00000008;
+        masterSystemTime_ = value;
+        onChanged();
+        return this;
+      }
+      /**
+       * <code>optional uint64 master_system_time = 4;</code>
+       *
+       * <pre>
+       * wall clock time from master
+       * </pre>
+       */
+      public Builder clearMasterSystemTime() {
+        bitField0_ = (bitField0_ & ~0x00000008);
+        masterSystemTime_ = 0L;
+        onChanged();
+        return this;
+      }
+
       // @@protoc_insertion_point(builder_scope:MergeRegionsRequest)
     }
 
@@ -23406,53 +23528,53 @@ public final class AdminProtos {
       "UpdateInfo\022\033\n\006region\030\001 \002(\0132\013.RegionInfo\022" +
       "\"\n\rfavored_nodes\030\002 \003(\0132\013.ServerName\".\n\032U" +
       "pdateFavoredNodesResponse\022\020\n\010response\030\001 " +
-      "\001(\r\"v\n\023MergeRegionsRequest\022\"\n\010region_a\030\001",
+      "\001(\r\"\222\001\n\023MergeRegionsRequest\022\"\n\010region_a\030",
-      " \002(\0132\020.RegionSpecifier\022\"\n\010region_b\030\002 \002(\013" +
+      "\001 \002(\0132\020.RegionSpecifier\022\"\n\010region_b\030\002 \002(" +
-      "2\020.RegionSpecifier\022\027\n\010forcible\030\003 \001(\010:\005fa" +
+      "\0132\020.RegionSpecifier\022\027\n\010forcible\030\003 \001(\010:\005f" +
-      "lse\"\026\n\024MergeRegionsResponse\"X\n\010WALEntry\022" +
+      "alse\022\032\n\022master_system_time\030\004 \001(\004\"\026\n\024Merg" +
-      "\024\n\003key\030\001 \002(\0132\007.WALKey\022\027\n\017key_value_bytes" +
+      "eRegionsResponse\"X\n\010WALEntry\022\024\n\003key\030\001 \002(" +
-      "\030\002 \003(\014\022\035\n\025associated_cell_count\030\003 \001(\005\"4\n" +
+      "\0132\007.WALKey\022\027\n\017key_value_bytes\030\002 \003(\014\022\035\n\025a" +
-      "\030ReplicateWALEntryRequest\022\030\n\005entry\030\001 \003(\013" +
+      "ssociated_cell_count\030\003 \001(\005\"4\n\030ReplicateW" +
-      "2\t.WALEntry\"\033\n\031ReplicateWALEntryResponse" +
+      "ALEntryRequest\022\030\n\005entry\030\001 \003(\0132\t.WALEntry" +
-      "\"\026\n\024RollWALWriterRequest\"0\n\025RollWALWrite" +
+      "\"\033\n\031ReplicateWALEntryResponse\"\026\n\024RollWAL" +
-      "rResponse\022\027\n\017region_to_flush\030\001 \003(\014\"#\n\021St" +
+      "WriterRequest\"0\n\025RollWALWriterResponse\022\027" +
-      "opServerRequest\022\016\n\006reason\030\001 \002(\t\"\024\n\022StopS",
+      "\n\017region_to_flush\030\001 \003(\014\"#\n\021StopServerReq",
-      "erverResponse\"\026\n\024GetServerInfoRequest\"B\n" +
+      "uest\022\016\n\006reason\030\001 \002(\t\"\024\n\022StopServerRespon" +
-      "\nServerInfo\022 \n\013server_name\030\001 \002(\0132\013.Serve" +
+      "se\"\026\n\024GetServerInfoRequest\"B\n\nServerInfo" +
-      "rName\022\022\n\nwebui_port\030\002 \001(\r\"9\n\025GetServerIn" +
+      "\022 \n\013server_name\030\001 \002(\0132\013.ServerName\022\022\n\nwe" +
-      "foResponse\022 \n\013server_info\030\001 \002(\0132\013.Server" +
+      "bui_port\030\002 \001(\r\"9\n\025GetServerInfoResponse\022" +
-      "Info\"\034\n\032UpdateConfigurationRequest\"\035\n\033Up" +
+      " \n\013server_info\030\001 \002(\0132\013.ServerInfo\"\034\n\032Upd" +
-      "dateConfigurationResponse2\325\010\n\014AdminServi" +
+      "ateConfigurationRequest\"\035\n\033UpdateConfigu" +
-      "ce\022>\n\rGetRegionInfo\022\025.GetRegionInfoReque" +
+      "rationResponse2\325\010\n\014AdminService\022>\n\rGetRe" +
-      "st\032\026.GetRegionInfoResponse\022;\n\014GetStoreFi" +
+      "gionInfo\022\025.GetRegionInfoRequest\032\026.GetReg" +
-      "le\022\024.GetStoreFileRequest\032\025.GetStoreFileR" +
+      "ionInfoResponse\022;\n\014GetStoreFile\022\024.GetSto" +
-      "esponse\022D\n\017GetOnlineRegion\022\027.GetOnlineRe",
+      "reFileRequest\032\025.GetStoreFileResponse\022D\n\017",
-      "gionRequest\032\030.GetOnlineRegionResponse\0225\n" +
+      "GetOnlineRegion\022\027.GetOnlineRegionRequest" +
-      "\nOpenRegion\022\022.OpenRegionRequest\032\023.OpenRe" +
+      "\032\030.GetOnlineRegionResponse\0225\n\nOpenRegion" +
-      "gionResponse\022;\n\014WarmupRegion\022\024.WarmupReg" +
+      "\022\022.OpenRegionRequest\032\023.OpenRegionRespons" +
-      "ionRequest\032\025.WarmupRegionResponse\0228\n\013Clo" +
+      "e\022;\n\014WarmupRegion\022\024.WarmupRegionRequest\032" +
-      "seRegion\022\023.CloseRegionRequest\032\024.CloseReg" +
+      "\025.WarmupRegionResponse\0228\n\013CloseRegion\022\023." +
-      "ionResponse\0228\n\013FlushRegion\022\023.FlushRegion" +
+      "CloseRegionRequest\032\024.CloseRegionResponse" +
-      "Request\032\024.FlushRegionResponse\0228\n\013SplitRe" +
+      "\0228\n\013FlushRegion\022\023.FlushRegionRequest\032\024.F" +
-      "gion\022\023.SplitRegionRequest\032\024.SplitRegionR" +
+      "lushRegionResponse\0228\n\013SplitRegion\022\023.Spli" +
-      "esponse\022>\n\rCompactRegion\022\025.CompactRegion" +
+      "tRegionRequest\032\024.SplitRegionResponse\022>\n\r" +
-      "Request\032\026.CompactRegionResponse\022;\n\014Merge",
+      "CompactRegion\022\025.CompactRegionRequest\032\026.C",
-      "Regions\022\024.MergeRegionsRequest\032\025.MergeReg" +
+      "ompactRegionResponse\022;\n\014MergeRegions\022\024.M" +
-      "ionsResponse\022J\n\021ReplicateWALEntry\022\031.Repl" +
+      "ergeRegionsRequest\032\025.MergeRegionsRespons" +
-      "icateWALEntryRequest\032\032.ReplicateWALEntry" +
+      "e\022J\n\021ReplicateWALEntry\022\031.ReplicateWALEnt" +
-      "Response\022?\n\006Replay\022\031.ReplicateWALEntryRe" +
+      "ryRequest\032\032.ReplicateWALEntryResponse\022?\n" +
-      "quest\032\032.ReplicateWALEntryResponse\022>\n\rRol" +
+      "\006Replay\022\031.ReplicateWALEntryRequest\032\032.Rep" +
-      "lWALWriter\022\025.RollWALWriterRequest\032\026.Roll" +
+      "licateWALEntryResponse\022>\n\rRollWALWriter\022" +
-      "WALWriterResponse\022>\n\rGetServerInfo\022\025.Get" +
+      "\025.RollWALWriterRequest\032\026.RollWALWriterRe" +
-      "ServerInfoRequest\032\026.GetServerInfoRespons" +
+      "sponse\022>\n\rGetServerInfo\022\025.GetServerInfoR" +
-      "e\0225\n\nStopServer\022\022.StopServerRequest\032\023.St" +
+      "equest\032\026.GetServerInfoResponse\0225\n\nStopSe" +
-      "opServerResponse\022M\n\022UpdateFavoredNodes\022\032",
+      "rver\022\022.StopServerRequest\032\023.StopServerRes",
-      ".UpdateFavoredNodesRequest\032\033.UpdateFavor" +
+      "ponse\022M\n\022UpdateFavoredNodes\022\032.UpdateFavo" +
-      "edNodesResponse\022P\n\023UpdateConfiguration\022\033" +
+      "redNodesRequest\032\033.UpdateFavoredNodesResp" +
-      ".UpdateConfigurationRequest\032\034.UpdateConf" +
+      "onse\022P\n\023UpdateConfiguration\022\033.UpdateConf" +
-      "igurationResponseBA\n*org.apache.hadoop.h" +
+      "igurationRequest\032\034.UpdateConfigurationRe" +
-      "base.protobuf.generatedB\013AdminProtosH\001\210\001" +
+      "sponseBA\n*org.apache.hadoop.hbase.protob" +
-      "\001\240\001\001"
+      "uf.generatedB\013AdminProtosH\001\210\001\001\240\001\001"
     };
     com.google.protobuf.Descriptors.FileDescriptor.InternalDescriptorAssigner assigner =
       new com.google.protobuf.Descriptors.FileDescriptor.InternalDescriptorAssigner() {
@@ -23596,7 +23718,7 @@ public final class AdminProtos {
           internal_static_MergeRegionsRequest_fieldAccessorTable = new
             com.google.protobuf.GeneratedMessage.FieldAccessorTable(
               internal_static_MergeRegionsRequest_descriptor,
-              new java.lang.String[] { "RegionA", "RegionB", "Forcible", });
+              new java.lang.String[] { "RegionA", "RegionB", "Forcible", "MasterSystemTime", });
           internal_static_MergeRegionsResponse_descriptor =
             getDescriptor().getMessageTypes().get(21);
           internal_static_MergeRegionsResponse_fieldAccessorTable = new

hbase-protocol/src/main/protobuf/Admin.proto

@@ -185,6 +185,8 @@ message MergeRegionsRequest {
   required RegionSpecifier region_a = 1;
   required RegionSpecifier region_b = 2;
   optional bool forcible = 3 [default = false];
+  // wall clock time from master
+  optional uint64 master_system_time = 4;
 }
 
 message MergeRegionsResponse {

hbase-server/src/main/java/org/apache/hadoop/hbase/master/RegionStateStore.java

@@ -40,6 +40,7 @@ import org.apache.hadoop.hbase.regionserver.Region;
 import org.apache.hadoop.hbase.regionserver.RegionServerServices;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.ConfigUtil;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.hbase.util.MultiHConnection;
 import org.apache.hadoop.hbase.zookeeper.MetaTableLocator;
 import org.apache.zookeeper.KeeperException;
@@ -256,6 +257,7 @@ public class RegionStateStore {
 
   void mergeRegions(HRegionInfo p,
       HRegionInfo a, HRegionInfo b, ServerName sn, int regionReplication) throws IOException {
-    MetaTableAccessor.mergeRegions(server.getConnection(), p, a, b, sn, regionReplication);
+    MetaTableAccessor.mergeRegions(server.getConnection(), p, a, b, sn, regionReplication,
+    		EnvironmentEdgeManager.currentTime());
   }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/CompactSplitThread.java

@@ -221,9 +221,9 @@ public class CompactSplitThread implements CompactionRequestor, PropagatingConfi
   }
 
   public synchronized void requestRegionsMerge(final Region a,
-      final Region b, final boolean forcible) {
+      final Region b, final boolean forcible, long masterSystemTime) {
     try {
-      mergePool.execute(new RegionMergeRequest(a, b, this.server, forcible));
+      mergePool.execute(new RegionMergeRequest(a, b, this.server, forcible, masterSystemTime));
       if (LOG.isDebugEnabled()) {
         LOG.debug("Region merge requested for " + a + "," + b + ", forcible="
             + forcible + ".  " + this);

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java

@@ -1312,6 +1312,7 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
       Region regionA = getRegion(request.getRegionA());
       Region regionB = getRegion(request.getRegionB());
       boolean forcible = request.getForcible();
+      long masterSystemTime = request.hasMasterSystemTime() ? request.getMasterSystemTime() : -1;
       regionA.startRegionOperation(Operation.MERGE_REGION);
       regionB.startRegionOperation(Operation.MERGE_REGION);
       if (regionA.getRegionInfo().getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID ||
@@ -1332,7 +1333,8 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
         long endTime = EnvironmentEdgeManager.currentTime();
         regionServer.metricsRegionServer.updateFlushTime(endTime - startTime);
       }
-      regionServer.compactSplitThread.requestRegionsMerge(regionA, regionB, forcible);
+      regionServer.compactSplitThread.requestRegionsMerge(regionA, regionB, forcible,
+          masterSystemTime);
       return MergeRegionsResponse.newBuilder().build();
     } catch (DroppedSnapshotException ex) {
       regionServer.abort("Replay of WAL required. Forcing server shutdown", ex);

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionMergeRequest.java

@@ -42,13 +42,16 @@ class RegionMergeRequest implements Runnable {
   private final HRegionServer server;
   private final boolean forcible;
   private TableLock tableLock;
+  private final long masterSystemTime;
 
-  RegionMergeRequest(Region a, Region b, HRegionServer hrs, boolean forcible) {
+  RegionMergeRequest(Region a, Region b, HRegionServer hrs, boolean forcible,
+    long masterSystemTime) {
     Preconditions.checkNotNull(hrs);
     this.region_a = (HRegion)a;
     this.region_b = (HRegion)b;
     this.server = hrs;
     this.forcible = forcible;
+    this.masterSystemTime = masterSystemTime;
   }
 
   @Override
@@ -67,7 +70,7 @@ class RegionMergeRequest implements Runnable {
     try {
       final long startTime = EnvironmentEdgeManager.currentTime();
       RegionMergeTransactionImpl mt = new RegionMergeTransactionImpl(region_a,
-          region_b, forcible);
+          region_b, forcible, masterSystemTime);
 
       //acquire a shared read lock on the table, so that table schema modifications
       //do not happen concurrently

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionMergeTransactionImpl.java

@@ -62,6 +62,7 @@ public class RegionMergeTransactionImpl implements RegionMergeTransaction {
   // We only merge adjacent regions if forcible is false
   private final boolean forcible;
   private boolean useCoordinationForAssignment;
+  private final long masterSystemTime;
 
   /*
    * Transaction state for listener, only valid during execute and
@@ -129,6 +130,17 @@ public class RegionMergeTransactionImpl implements RegionMergeTransaction {
    */
   public RegionMergeTransactionImpl(final Region a, final Region b,
       final boolean forcible) {
+    this(a, b, forcible, EnvironmentEdgeManager.currentTime());
+  }
+  /**
+   * Constructor
+   * @param a region a to merge
+   * @param b region b to merge
+   * @param forcible if false, we will only merge adjacent regions
+   * @param masterSystemTime the time at the master side
+   */
+  public RegionMergeTransactionImpl(final Region a, final Region b,
+      final boolean forcible, long masterSystemTime) {
     if (a.getRegionInfo().compareTo(b.getRegionInfo()) <= 0) {
       this.region_a = (HRegion)a;
       this.region_b = (HRegion)b;
@@ -137,6 +149,7 @@ public class RegionMergeTransactionImpl implements RegionMergeTransaction {
       this.region_b = (HRegion)a;
     }
     this.forcible = forcible;
+    this.masterSystemTime = masterSystemTime;
     this.mergesdir = region_a.getRegionFileSystem().getMergesDir();
   }
 
@@ -168,6 +181,7 @@ public class RegionMergeTransactionImpl implements RegionMergeTransaction {
    * @return <code>true</code> if the regions are mergeable else
    *         <code>false</code> if they are not (e.g. its already closed, etc.).
    */
+  @Override
   public boolean prepare(final RegionServerServices services) throws IOException {
     if (!region_a.getTableDesc().getTableName()
         .equals(region_b.getTableDesc().getTableName())) {
@@ -232,6 +246,7 @@ public class RegionMergeTransactionImpl implements RegionMergeTransaction {
    * @throws IOException
    * @see #rollback(Server, RegionServerServices)
    */
+  @Override
   public HRegion execute(final Server server,
       final RegionServerServices services) throws IOException {
     this.server = server;
@@ -335,7 +350,7 @@ public class RegionMergeTransactionImpl implements RegionMergeTransaction {
       if (metaEntries.isEmpty()) {
         MetaTableAccessor.mergeRegions(server.getConnection(),
           mergedRegion.getRegionInfo(), region_a.getRegionInfo(), region_b.getRegionInfo(),
-          server.getServerName(), region_a.getTableDesc().getRegionReplication());
+          server.getServerName(), region_a.getTableDesc().getRegionReplication(), masterSystemTime);
       } else {
         mergeRegionsAndPutMetaEntries(server.getConnection(),
           mergedRegion.getRegionInfo(), region_a.getRegionInfo(), region_b.getRegionInfo(),
@@ -367,16 +382,19 @@ public class RegionMergeTransactionImpl implements RegionMergeTransaction {
       int regionReplication) throws IOException {
     HRegionInfo copyOfMerged = new HRegionInfo(mergedRegion);
 
+    // use the maximum of what master passed us vs local time.
+    long time = Math.max(EnvironmentEdgeManager.currentTime(), masterSystemTime);
+
     // Put for parent
-    Put putOfMerged = MetaTableAccessor.makePutFromRegionInfo(copyOfMerged);
+    Put putOfMerged = MetaTableAccessor.makePutFromRegionInfo(copyOfMerged, time);
     putOfMerged.add(HConstants.CATALOG_FAMILY, HConstants.MERGEA_QUALIFIER,
       regionA.toByteArray());
     putOfMerged.add(HConstants.CATALOG_FAMILY, HConstants.MERGEB_QUALIFIER,
       regionB.toByteArray());
     mutations.add(putOfMerged);
     // Deletes for merging regions
-    Delete deleteA = MetaTableAccessor.makeDeleteFromRegionInfo(regionA);
+    Delete deleteA = MetaTableAccessor.makeDeleteFromRegionInfo(regionA, time);
-    Delete deleteB = MetaTableAccessor.makeDeleteFromRegionInfo(regionB);
+    Delete deleteB = MetaTableAccessor.makeDeleteFromRegionInfo(regionB, time);
     mutations.add(deleteA);
     mutations.add(deleteB);
 
@@ -663,6 +681,7 @@ public class RegionMergeTransactionImpl implements RegionMergeTransaction {
    *         of no return and so now need to abort the server to minimize
    *         damage.
    */
+  @Override
   @SuppressWarnings("deprecation")
   public boolean rollback(final Server server,
       final RegionServerServices services) throws IOException {

hbase-server/src/test/java/org/apache/hadoop/hbase/TestMetaTableAccessor.java

@@ -464,7 +464,8 @@ public class TestMetaTableAccessor {
       List<HRegionInfo> regionInfos = Lists.newArrayList(parentA, parentB);
       MetaTableAccessor.addRegionsToMeta(connection, regionInfos, 3);
 
-      MetaTableAccessor.mergeRegions(connection, merged, parentA, parentB, serverName0, 3);
+      MetaTableAccessor.mergeRegions(connection, merged, parentA, parentB, serverName0, 3,
+          HConstants.LATEST_TIMESTAMP);
 
       assertEmptyMetaLocation(meta, merged.getRegionName(), 1);
       assertEmptyMetaLocation(meta, merged.getRegionName(), 2);
@@ -473,6 +474,9 @@ public class TestMetaTableAccessor {
     }
   }
 
+  /**
+   * Tests whether maximum of masters system time versus RSs local system time is used
+   */
   @Test
   public void testMastersSystemTimeIsUsedInUpdateLocations() throws IOException {
     long regionId = System.currentTimeMillis();
@@ -509,5 +513,57 @@ public class TestMetaTableAccessor {
       meta.close();
     }
   }
+
+  @Test
+  public void testMastersSystemTimeIsUsedInMergeRegions() throws IOException {
+    long regionId = System.currentTimeMillis();
+    HRegionInfo regionInfoA = new HRegionInfo(TableName.valueOf("table_foo"),
+      HConstants.EMPTY_START_ROW, new byte[] {'a'}, false, regionId, 0);
+    HRegionInfo regionInfoB = new HRegionInfo(TableName.valueOf("table_foo"),
+      new byte[] {'a'}, HConstants.EMPTY_END_ROW, false, regionId, 0);
+    HRegionInfo mergedRegionInfo = new HRegionInfo(TableName.valueOf("table_foo"),
+      HConstants.EMPTY_START_ROW, HConstants.EMPTY_END_ROW, false, regionId, 0);
+
+    ServerName sn = ServerName.valueOf("bar", 0, 0);
+    Table meta = MetaTableAccessor.getMetaHTable(connection);
+    try {
+      List<HRegionInfo> regionInfos = Lists.newArrayList(regionInfoA, regionInfoB);
+      MetaTableAccessor.addRegionsToMeta(connection, regionInfos, 1);
+
+      // write the serverName column with a big current time, but set the masters time as even
+      // bigger. When region merge deletes the rows for regionA and regionB, the serverName columns
+      // should not be seen by the following get
+      long serverNameTime = EnvironmentEdgeManager.currentTime()   + 100000000;
+      long masterSystemTime = EnvironmentEdgeManager.currentTime() + 123456789;
+
+      // write the serverName columns
+      MetaTableAccessor.updateRegionLocation(connection, regionInfoA, sn, 1, serverNameTime);
+
+      // assert that we have the serverName column with expected ts
+      Get get = new Get(mergedRegionInfo.getRegionName());
+      Result result = meta.get(get);
+      Cell serverCell = result.getColumnLatestCell(HConstants.CATALOG_FAMILY,
+          MetaTableAccessor.getServerColumn(0));
+      assertNotNull(serverCell);
+      assertEquals(serverNameTime, serverCell.getTimestamp());
+
+      // now merge the regions, effectively deleting the rows for region a and b.
+      MetaTableAccessor.mergeRegions(connection, mergedRegionInfo,
+        regionInfoA, regionInfoB, sn, 1, masterSystemTime);
+
+      result = meta.get(get);
+      serverCell = result.getColumnLatestCell(HConstants.CATALOG_FAMILY,
+          MetaTableAccessor.getServerColumn(0));
+      Cell startCodeCell = result.getColumnLatestCell(HConstants.CATALOG_FAMILY,
+        MetaTableAccessor.getStartCodeColumn(0));
+      Cell seqNumCell = result.getColumnLatestCell(HConstants.CATALOG_FAMILY,
+        MetaTableAccessor.getSeqNumColumn(0));
+      assertNull(serverCell);
+      assertNull(startCodeCell);
+      assertNull(seqNumCell);
+    } finally {
+      meta.close();
+    }
+  }
 }