fix issue #81 - incorrect partition id in sst mode (#82)

* fix issue #81

* take care of endianess when converting byte array to long

* take care of endieness in a good way

exchange-common/src/main/scala/com/vesoft/exchange/common/utils/NebulaUtils.scala

@@ -6,6 +6,9 @@
 package com.vesoft.exchange.common.utils
 
 import java.nio.charset.Charset
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+
 
 import com.google.common.primitives.UnsignedLong
 import com.vesoft.exchange.common.MetaProvider
@@ -85,11 +88,18 @@ object NebulaUtils {
     s
   }
 
+
+
   def getPartitionId(id: String, partitionSize: Int, vidType: VidType.Value): Int = {
     val hashValue: Long = if (vidType == VidType.STRING) {
       // todo charset must be the same with Nebula Space
       val byteId = id.getBytes(Charset.forName("UTF-8"))
-      MurmurHash2.hash64(byteId, byteId.length, 0xc70f6907)
+      if (byteId.length == 8) {
+        //byte array to long, need to take care of endianess
+        ByteBuffer.wrap(byteId).order(ByteOrder.nativeOrder).getLong
+      } else {
+        MurmurHash2.hash64(byteId, byteId.length, 0xc70f6907)
+      }
     } else {
       id.toLong
     }