Add a new EntryType for deletion with timestamp (#7195)

Summary:
Add `kEntryDeleteWithTimestamp` to `EntryType` which is a public API.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7195

Test Plan: make check

Reviewed By: ajkr

Differential Revision: D22914704

Pulled By: riversand963

fbshipit-source-id: 886f73c6b70c527cad1c8fc9fc8d3afe60e1ea39

HISTORY.md

@@ -12,6 +12,9 @@
 ### Performance Improvements
 * Reduce thread number for multiple DB instances by re-using one global thread for statistics dumping and persisting.
 
+### Public API Change
+* Expose kTypeDeleteWithTimestamp in EntryType and update GetEntryType() accordingly.
+
 ## 6.12 (2020-07-28)
 ### Public API Change
 * Encryption file classes now exposed for inheritance in env_encryption.h

db/dbformat.cc

@@ -32,6 +32,8 @@ EntryType GetEntryType(ValueType value_type) {
       return kEntryPut;
     case kTypeDeletion:
       return kEntryDelete;
+    case kTypeDeletionWithTimestamp:
+      return kEntryDeleteWithTimestamp;
     case kTypeSingleDeletion:
       return kEntrySingleDelete;
     case kTypeMerge:

include/rocksdb/types.h

@@ -18,6 +18,7 @@ typedef uint64_t SequenceNumber;
 const SequenceNumber kMinUnCommittedSeq = 1;  // 0 is always committed
 
 // User-oriented representation of internal key types.
+// Ordering of this enum entries should not change.
 enum EntryType {
   kEntryPut,
   kEntryDelete,
@@ -25,6 +26,7 @@ enum EntryType {
   kEntryMerge,
   kEntryRangeDeletion,
   kEntryBlobIndex,
+  kEntryDeleteWithTimestamp,
   kEntryOther,
 };