Test merge op covered by range deletion in memtable

Summary:
It's a test case for #1797. Also got rid of kTypeDeletion in the conditional since we treat it the same as kTypeRangeDeletion.
Closes https://github.com/facebook/rocksdb/pull/1800

Differential Revision: D4451300

Pulled By: ajkr

fbshipit-source-id: b39dda1

db/db_range_del_test.cc

@@ -601,6 +601,36 @@ TEST_F(DBRangeDelTest, GetCoveredKeyFromSst) {
   db_->ReleaseSnapshot(snapshot);
 }
 
+TEST_F(DBRangeDelTest, GetCoveredMergeOperandFromMemtable) {
+  const int kNumMergeOps = 10;
+  Options opts = CurrentOptions();
+  opts.merge_operator = MergeOperators::CreateUInt64AddOperator();
+  Reopen(opts);
+
+  for (int i = 0; i < kNumMergeOps; ++i) {
+    std::string val;
+    PutFixed64(&val, i);
+    db_->Merge(WriteOptions(), "key", val);
+    if (i == kNumMergeOps / 2) {
+      // deletes [0, 5]
+      db_->DeleteRange(WriteOptions(), db_->DefaultColumnFamily(), "key",
+                       "key_");
+    }
+  }
+
+  ReadOptions read_opts;
+  std::string expected, actual;
+  ASSERT_OK(db_->Get(read_opts, "key", &actual));
+  PutFixed64(&expected, 30);  // 6+7+8+9
+  ASSERT_EQ(expected, actual);
+
+  expected.clear();
+  read_opts.ignore_range_deletions = true;
+  ASSERT_OK(db_->Get(read_opts, "key", &actual));
+  PutFixed64(&expected, 45);  // 0+1+2+...+9
+  ASSERT_EQ(expected, actual);
+}
+
 TEST_F(DBRangeDelTest, GetIgnoresRangeDeletions) {
   Options opts = CurrentOptions();
   opts.max_write_buffer_number = 4;

db/memtable.cc

@@ -560,7 +560,7 @@ static bool SaveValue(void* arg, const char* entry) {
     ValueType type;
     UnPackSequenceAndType(tag, &s->seq, &type);
 
-    if ((type == kTypeValue || type == kTypeDeletion || type == kTypeMerge) &&
+    if ((type == kTypeValue || type == kTypeMerge) &&
         range_del_agg->ShouldDelete(Slice(key_ptr, key_length))) {
       type = kTypeRangeDeletion;
     }