Fix a bug in range scan with merge and deletion with timestamp (#10915)

Summary:
When performing Merge during range scan, iterator should understand value types of kDeletionWithTimestamp.

Also add an additional check in debug mode to MergeHelper, and account for the presence of compaction filter.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10915

Test Plan: make check

Reviewed By: ltamasi

Differential Revision: D40960039

Pulled By: riversand963

fbshipit-source-id: dd79d86d7c79d05755bb939a3d94e0c53ddd7f59

db/db_iter.cc

@@ -528,7 +528,8 @@ bool DBIter::MergeValuesNewToOld() {
       // hit the next user key, stop right here
       break;
     }
-    if (kTypeDeletion == ikey.type || kTypeSingleDeletion == ikey.type) {
+    if (kTypeDeletion == ikey.type || kTypeSingleDeletion == ikey.type ||
+        kTypeDeletionWithTimestamp == ikey.type) {
       // hit a delete with the same user key, stop right here
       // iter_ is positioned after delete
       iter_.Next();
@@ -957,7 +958,8 @@ bool DBIter::FindValueForCurrentKey() {
     case kTypeMerge:
       current_entry_is_merged_ = true;
       if (last_not_merge_type == kTypeDeletion ||
-          last_not_merge_type == kTypeSingleDeletion) {
+          last_not_merge_type == kTypeSingleDeletion ||
+          last_not_merge_type == kTypeDeletionWithTimestamp) {
         s = Merge(nullptr, saved_key_.GetUserKey());
         if (!s.ok()) {
           return false;
@@ -1164,7 +1166,8 @@ bool DBIter::FindValueForCurrentKeyUsingSeek() {
                                                 saved_key_.GetUserKey())) {
       break;
     }
-    if (ikey.type == kTypeDeletion || ikey.type == kTypeSingleDeletion) {
+    if (ikey.type == kTypeDeletion || ikey.type == kTypeSingleDeletion ||
+        ikey.type == kTypeDeletionWithTimestamp) {
       break;
     }
     if (!iter_.PrepareValue()) {

db/db_with_timestamp_basic_test.cc

@@ -3799,6 +3799,77 @@ TEST_F(DBBasicTestWithTimestamp, MergeBasic) {
 
   Close();
 }
+
+TEST_F(DBBasicTestWithTimestamp, MergeAfterDeletion) {
+  Options options = GetDefaultOptions();
+  options.create_if_missing = true;
+  const size_t kTimestampSize = Timestamp(0, 0).size();
+  TestComparator test_cmp(kTimestampSize);
+  options.comparator = &test_cmp;
+  options.merge_operator = std::make_shared<StringAppendTESTOperator>('.');
+  DestroyAndReopen(options);
+
+  ColumnFamilyHandle* const column_family = db_->DefaultColumnFamily();
+
+  const size_t num_keys_per_file = 10;
+  const size_t num_merges_per_key = 2;
+  for (size_t i = 0; i < num_keys_per_file; ++i) {
+    std::string ts = Timestamp(i + 10000, 0);
+    Status s = db_->Delete(WriteOptions(), Key1(i), ts);
+    ASSERT_OK(s);
+    for (size_t j = 1; j <= num_merges_per_key; ++j) {
+      ts = Timestamp(i + 10000 + j, 0);
+      s = db_->Merge(WriteOptions(), column_family, Key1(i), ts,
+                     std::to_string(j));
+      ASSERT_OK(s);
+    }
+  }
+
+  const auto verify_db = [&]() {
+    ReadOptions read_opts;
+    std::string read_ts_str = Timestamp(20000, 0);
+    Slice ts = read_ts_str;
+    read_opts.timestamp = &ts;
+    std::unique_ptr<Iterator> it(db_->NewIterator(read_opts));
+    size_t count = 0;
+    for (it->SeekToFirst(); it->Valid(); it->Next(), ++count) {
+      std::string key = Key1(count);
+      ASSERT_EQ(key, it->key());
+      std::string value;
+      for (size_t j = 1; j <= num_merges_per_key; ++j) {
+        value.append(std::to_string(j));
+        if (j < num_merges_per_key) {
+          value.push_back('.');
+        }
+      }
+      ASSERT_EQ(value, it->value());
+      std::string ts1 = Timestamp(count + 10000 + num_merges_per_key, 0);
+      ASSERT_EQ(ts1, it->timestamp());
+    }
+    ASSERT_OK(it->status());
+    ASSERT_EQ(num_keys_per_file, count);
+    for (it->SeekToLast(); it->Valid(); it->Prev(), --count) {
+      std::string key = Key1(count - 1);
+      ASSERT_EQ(key, it->key());
+      std::string value;
+      for (size_t j = 1; j <= num_merges_per_key; ++j) {
+        value.append(std::to_string(j));
+        if (j < num_merges_per_key) {
+          value.push_back('.');
+        }
+      }
+      ASSERT_EQ(value, it->value());
+      std::string ts1 = Timestamp(count - 1 + 10000 + num_merges_per_key, 0);
+      ASSERT_EQ(ts1, it->timestamp());
+    }
+    ASSERT_OK(it->status());
+    ASSERT_EQ(0, count);
+  };
+
+  verify_db();
+
+  Close();
+}
 }  // namespace ROCKSDB_NAMESPACE
 
 int main(int argc, char** argv) {

db/merge_helper.cc

@@ -13,6 +13,7 @@
 #include "db/compaction/compaction_iteration_stats.h"
 #include "db/dbformat.h"
 #include "db/wide/wide_column_serialization.h"
+#include "logging/logging.h"
 #include "monitoring/perf_context_imp.h"
 #include "monitoring/statistics.h"
 #include "port/likely.h"
@@ -255,6 +256,8 @@ Status MergeHelper::MergeUntil(InternalIterator* iter,
   assert(s.ok());
   if (!s.ok()) return s;
 
+  assert(kTypeMerge == orig_ikey.type);
+
   bool hit_the_next_user_key = false;
   int cmp_with_full_history_ts_low = 0;
   for (; iter->Valid(); iter->Next(), original_key_is_iter = false) {
@@ -460,10 +463,15 @@ Status MergeHelper::MergeUntil(InternalIterator* iter,
   }
 
   if (cmp_with_full_history_ts_low >= 0) {
-    // If we reach here, and ts_sz == 0, it means compaction cannot perform
+    size_t num_merge_operands = merge_context_.GetNumOperands();
-    // merge with an earlier internal key, thus merge_context_.GetNumOperands()
+    if (ts_sz && num_merge_operands > 1) {
-    // is 1.
+      // We do not merge merge operands with different timestamps if they are
-    assert(ts_sz == 0 || merge_context_.GetNumOperands() == 1);
+      // not eligible for GC.
+      ROCKS_LOG_ERROR(logger_, "ts_sz=%d, %d merge oprands",
+                      static_cast<int>(ts_sz),
+                      static_cast<int>(num_merge_operands));
+      assert(false);
+    }
   }
 
   if (merge_context_.GetNumOperands() == 0) {