Make range deletion inclusive-exclusive

Summary:
This makes it easier to implement future optimizations like range collapsing.
Closes https://github.com/facebook/rocksdb/pull/1504

Differential Revision: D4172214

Pulled By: ajkr

fbshipit-source-id: ac4942f

db/flush_job_test.cc

@@ -125,9 +125,9 @@ TEST_F(FlushJobTest, NonEmpty) {
       inserted_keys.insert({internal_key.Encode().ToString(), value});
     }
   }
-  new_mem->Add(SequenceNumber(10000), kTypeRangeDeletion, "9995", "9999");
+  new_mem->Add(SequenceNumber(10000), kTypeRangeDeletion, "9995", "9999a");
   InternalKey internal_key("9995", SequenceNumber(10000), kTypeRangeDeletion);
-  inserted_keys.insert({internal_key.Encode().ToString(), "9999"});
+  inserted_keys.insert({internal_key.Encode().ToString(), "9999a"});
 
   autovector<MemTable*> to_delete;
   cfd->imm()->Add(new_mem, &to_delete);
@@ -147,7 +147,7 @@ TEST_F(FlushJobTest, NonEmpty) {
   ASSERT_OK(flush_job.Run(&fd));
   mutex_.Unlock();
   ASSERT_EQ(ToString(0), fd.smallest.user_key().ToString());
-  ASSERT_EQ(ToString(9999),
+  ASSERT_EQ("9999a",
             fd.largest.user_key().ToString());  // range tombstone end key
   ASSERT_EQ(1, fd.smallest_seqno);
   ASSERT_EQ(10000, fd.largest_seqno);  // range tombstone seqnum 10000

db/range_del_aggregator.cc

@@ -41,7 +41,7 @@ bool RangeDelAggregator::ShouldDelete(const ParsedInternalKey& parsed) {
       break;
     }
     if (parsed.sequence < tombstone.seq_ &&
-        icmp_.user_comparator()->Compare(parsed.user_key, tombstone.end_key_) <=
+        icmp_.user_comparator()->Compare(parsed.user_key, tombstone.end_key_) <
             0) {
       return true;
     }