Support to create a CF by importing multiple non-overlapping CFs (#11378)

Summary:
The original Feature Request is from [https://github.com/facebook/rocksdb/issues/11317](https://github.com/facebook/rocksdb/issues/11317).
Flink uses rocksdb as the state backend,  all DB options are the same, and the keys of each DB instance are adjacent and there is no key overlap between two db instances.
In the Flink rescaling scenario, it is necessary to quickly split the DB according to a certain key range or quickly merge multiple DBs into one.

This PR is mainly used to quickly merge multiple DBs into one.

We hope to extend the function of `CreateColumnFamilyWithImports` to support creating ColumnFamily by importing multiple ColumnFamily with no overlapping keys.

The import logic is almost the same as `CreateColumnFamilyWithImport`, but it will check whether there is key overlap between CF when importing. The import will fail if there are key overlaps.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/11378

Reviewed By: ajkr

Differential Revision: D46413709

Pulled By: cbi42

fbshipit-source-id: 846d0049fad11c59cf460fa846c345b26c658dfb

db/db_impl/compacted_db_impl.h

@@ -118,12 +118,13 @@ class CompactedDBImpl : public DBImpl {
       const IngestExternalFileOptions& /*ingestion_options*/) override {
     return Status::NotSupported("Not supported in compacted db mode.");
   }
+
   using DB::CreateColumnFamilyWithImport;
   virtual Status CreateColumnFamilyWithImport(
       const ColumnFamilyOptions& /*options*/,
       const std::string& /*column_family_name*/,
       const ImportColumnFamilyOptions& /*import_options*/,
-      const ExportImportFilesMetaData& /*metadata*/,
+      const std::vector<const ExportImportFilesMetaData*>& /*metadatas*/,
       ColumnFamilyHandle** /*handle*/) override {
     return Status::NotSupported("Not supported in compacted db mode.");
   }

db/db_impl/db_impl.cc

@@ -5575,15 +5575,25 @@ Status DBImpl::IngestExternalFiles(
 Status DBImpl::CreateColumnFamilyWithImport(
     const ColumnFamilyOptions& options, const std::string& column_family_name,
     const ImportColumnFamilyOptions& import_options,
-    const ExportImportFilesMetaData& metadata, ColumnFamilyHandle** handle) {
+    const std::vector<const ExportImportFilesMetaData*>& metadatas,
+    ColumnFamilyHandle** handle) {
   assert(handle != nullptr);
   assert(*handle == nullptr);
   // TODO: plumb Env::IOActivity
   const ReadOptions read_options;
   std::string cf_comparator_name = options.comparator->Name();
-  if (cf_comparator_name != metadata.db_comparator_name) {
+
+  size_t total_file_num = 0;
+  std::vector<std::vector<LiveFileMetaData*>> metadata_files(metadatas.size());
+  for (size_t i = 0; i < metadatas.size(); i++) {
+    if (cf_comparator_name != metadatas[i]->db_comparator_name) {
       return Status::InvalidArgument("Comparator name mismatch");
     }
+    for (auto& file : metadatas[i]->files) {
+      metadata_files[i].push_back((LiveFileMetaData*)&file);
+    }
+    total_file_num += metadatas[i]->files.size();
+  }
 
   // Create column family.
   auto status = CreateColumnFamily(options, column_family_name, handle);
@@ -5596,7 +5606,7 @@ Status DBImpl::CreateColumnFamilyWithImport(
   auto cfd = cfh->cfd();
   ImportColumnFamilyJob import_job(versions_.get(), cfd, immutable_db_options_,
                                    file_options_, import_options,
-                                   metadata.files, io_tracer_);
+                                   metadata_files, io_tracer_);
 
   SuperVersionContext dummy_sv_ctx(/* create_superversion */ true);
   VersionEdit dummy_edit;
@@ -5619,7 +5629,7 @@ Status DBImpl::CreateColumnFamilyWithImport(
       // reuse the file number that has already assigned to the internal file,
       // and this will overwrite the external file. To protect the external
       // file, we have to make sure the file number will never being reused.
-      next_file_number = versions_->FetchAddFileNumber(metadata.files.size());
+      next_file_number = versions_->FetchAddFileNumber(total_file_num);
       auto cf_options = cfd->GetLatestMutableCFOptions();
       status =
           versions_->LogAndApply(cfd, *cf_options, read_options, &dummy_edit,

db/db_impl/db_impl.h

@@ -531,7 +531,7 @@ class DBImpl : public DB {
   virtual Status CreateColumnFamilyWithImport(
       const ColumnFamilyOptions& options, const std::string& column_family_name,
       const ImportColumnFamilyOptions& import_options,
-      const ExportImportFilesMetaData& metadata,
+      const std::vector<const ExportImportFilesMetaData*>& metadatas,
       ColumnFamilyHandle** handle) override;
 
   using DB::ClipColumnFamily;

db/db_impl/db_impl_readonly.h

@@ -137,7 +137,7 @@ class DBImplReadOnly : public DBImpl {
       const ColumnFamilyOptions& /*options*/,
       const std::string& /*column_family_name*/,
       const ImportColumnFamilyOptions& /*import_options*/,
-      const ExportImportFilesMetaData& /*metadata*/,
+      const std::vector<const ExportImportFilesMetaData*>& /*metadatas*/,
       ColumnFamilyHandle** /*handle*/) override {
     return Status::NotSupported("Not supported operation in read only mode.");
   }

db/db_test.cc

@@ -3097,7 +3097,7 @@ class ModelDB : public DB {
       const ColumnFamilyOptions& /*options*/,
       const std::string& /*column_family_name*/,
       const ImportColumnFamilyOptions& /*import_options*/,
-      const ExportImportFilesMetaData& /*metadata*/,
+      const std::vector<const ExportImportFilesMetaData*>& /*metadatas*/,
       ColumnFamilyHandle** /*handle*/) override {
     return Status::NotSupported("Not implemented.");
   }

db/import_column_family_job.cc

@@ -29,9 +29,15 @@ namespace ROCKSDB_NAMESPACE {
 Status ImportColumnFamilyJob::Prepare(uint64_t next_file_number,
                                       SuperVersion* sv) {
   Status status;
-
+  std::vector<ColumnFamilyIngestFileInfo> cf_ingest_infos;
+  for (const auto& metadata_per_cf : metadatas_) {
     // Read the information of files we are importing
-  for (const auto& file_metadata : metadata_) {
+    ColumnFamilyIngestFileInfo cf_file_info;
+    InternalKey smallest, largest;
+    int num_files = 0;
+    std::vector<IngestedFileInfo> files_to_import_per_cf;
+    for (size_t i = 0; i < metadata_per_cf.size(); i++) {
+      auto file_metadata = *metadata_per_cf[i];
       const auto file_path = file_metadata.db_path + "/" + file_metadata.name;
       IngestedFileInfo file_to_import;
       status = GetIngestedFileInfo(file_path, next_file_number++, sv,
@@ -39,43 +45,84 @@ Status ImportColumnFamilyJob::Prepare(uint64_t next_file_number,
       if (!status.ok()) {
         return status;
       }
-    files_to_import_.push_back(file_to_import);
-  }
 
-  auto num_files = files_to_import_.size();
-  if (num_files == 0) {
-    status = Status::InvalidArgument("The list of files is empty");
+      if (file_to_import.num_entries == 0) {
+        status = Status::InvalidArgument("File contain no entries");
         return status;
       }
 
-  for (const auto& f : files_to_import_) {
-    if (f.num_entries == 0) {
-      status = Status::InvalidArgument("File contain no entries");
+      if (!file_to_import.smallest_internal_key.Valid() ||
+          !file_to_import.largest_internal_key.Valid()) {
+        status = Status::Corruption("File has corrupted keys");
         return status;
       }
 
-    if (!f.smallest_internal_key.Valid() || !f.largest_internal_key.Valid()) {
-      status = Status::Corruption("File has corrupted keys");
+      files_to_import_per_cf.push_back(file_to_import);
+      num_files++;
+
+      // Calculate the smallest and largest keys of all files in this CF
+      if (i == 0) {
+        smallest = file_to_import.smallest_internal_key;
+        largest = file_to_import.largest_internal_key;
+      } else {
+        if (cfd_->internal_comparator().Compare(
+                smallest, file_to_import.smallest_internal_key) < 0) {
+          smallest = file_to_import.smallest_internal_key;
+        }
+        if (cfd_->internal_comparator().Compare(
+                largest, file_to_import.largest_internal_key) > 0) {
+          largest = file_to_import.largest_internal_key;
+        }
+      }
+    }
+
+    if (num_files == 0) {
+      status = Status::InvalidArgument("The list of files is empty");
+      return status;
+    }
+    files_to_import_.push_back(files_to_import_per_cf);
+    cf_file_info.smallest_internal_key = smallest;
+    cf_file_info.largest_internal_key = largest;
+    cf_ingest_infos.push_back(cf_file_info);
+  }
+
+  std::sort(cf_ingest_infos.begin(), cf_ingest_infos.end(),
+            [this](const ColumnFamilyIngestFileInfo& info1,
+                   const ColumnFamilyIngestFileInfo& info2) {
+              return cfd_->user_comparator()->Compare(
+                         info1.smallest_internal_key.user_key(),
+                         info2.smallest_internal_key.user_key()) < 0;
+            });
+
+  for (size_t i = 0; i + 1 < cf_ingest_infos.size(); i++) {
+    if (cfd_->user_comparator()->Compare(
+            cf_ingest_infos[i].largest_internal_key.user_key(),
+            cf_ingest_infos[i + 1].smallest_internal_key.user_key()) >= 0) {
+      status = Status::InvalidArgument("CFs have overlapping ranges");
       return status;
     }
   }
 
   // Copy/Move external files into DB
   auto hardlink_files = import_options_.move_files;
-  for (auto& f : files_to_import_) {
+
+  for (auto& files_to_import_per_cf : files_to_import_) {
+    for (auto& f : files_to_import_per_cf) {
       const auto path_outside_db = f.external_file_path;
       const auto path_inside_db = TableFileName(
           cfd_->ioptions()->cf_paths, f.fd.GetNumber(), f.fd.GetPathId());
 
       if (hardlink_files) {
-      status =
-          fs_->LinkFile(path_outside_db, path_inside_db, IOOptions(), nullptr);
+        status = fs_->LinkFile(path_outside_db, path_inside_db, IOOptions(),
+                               nullptr);
         if (status.IsNotSupported()) {
-        // Original file is on a different FS, use copy instead of hard linking
+          // Original file is on a different FS, use copy instead of hard
+          // linking
           hardlink_files = false;
           ROCKS_LOG_INFO(db_options_.info_log,
                          "Try to link file %s but it's not supported : %s",
-                       f.internal_file_path.c_str(), status.ToString().c_str());
+                         f.internal_file_path.c_str(),
+                         status.ToString().c_str());
         }
       }
       if (!hardlink_files) {
@@ -89,10 +136,15 @@ Status ImportColumnFamilyJob::Prepare(uint64_t next_file_number,
       f.copy_file = !hardlink_files;
       f.internal_file_path = path_inside_db;
     }
+    if (!status.ok()) {
+      break;
+    }
+  }
 
   if (!status.ok()) {
     // We failed, remove all files that we copied into the db
-    for (const auto& f : files_to_import_) {
+    for (auto& files_to_import_per_cf : files_to_import_) {
+      for (auto& f : files_to_import_per_cf) {
         if (f.internal_file_path.empty()) {
           break;
         }
@@ -105,6 +157,7 @@ Status ImportColumnFamilyJob::Prepare(uint64_t next_file_number,
         }
       }
     }
+  }
 
   return status;
 }
@@ -134,9 +187,11 @@ Status ImportColumnFamilyJob::Run() {
       nullptr /* src_vstorage */, cfd_->ioptions()->force_consistency_checks,
       EpochNumberRequirement::kMightMissing);
   Status s;
+
   for (size_t i = 0; s.ok() && i < files_to_import_.size(); ++i) {
-    const auto& f = files_to_import_[i];
-    const auto& file_metadata = metadata_[i];
+    for (size_t j = 0; s.ok() && j < files_to_import_[i].size(); ++j) {
+      const auto& f = files_to_import_[i][j];
+      const auto& file_metadata = *metadatas_[i][j];
 
       uint64_t tail_size = 0;
       bool contain_no_data_blocks = f.table_properties.num_entries > 0 &&
@@ -153,11 +208,14 @@ Status ImportColumnFamilyJob::Run() {
           file_metadata.level, f.fd.GetNumber(), f.fd.GetPathId(),
           f.fd.GetFileSize(), f.smallest_internal_key, f.largest_internal_key,
           file_metadata.smallest_seqno, file_metadata.largest_seqno, false,
-        file_metadata.temperature, kInvalidBlobFileNumber, oldest_ancester_time,
-        current_time, file_metadata.epoch_number, kUnknownFileChecksum,
-        kUnknownFileChecksumFuncName, f.unique_id, 0, tail_size);
+          file_metadata.temperature, kInvalidBlobFileNumber,
+          oldest_ancester_time, current_time, file_metadata.epoch_number,
+          kUnknownFileChecksum, kUnknownFileChecksumFuncName, f.unique_id, 0,
+          tail_size);
       s = dummy_version_builder.Apply(&dummy_version_edit);
     }
+  }
+
   if (s.ok()) {
     s = dummy_version_builder.SaveTo(&dummy_vstorage);
   }
@@ -198,7 +256,8 @@ Status ImportColumnFamilyJob::Run() {
 void ImportColumnFamilyJob::Cleanup(const Status& status) {
   if (!status.ok()) {
     // We failed to add files to the database remove all the files we copied.
-    for (const auto& f : files_to_import_) {
+    for (auto& files_to_import_per_cf : files_to_import_) {
+      for (auto& f : files_to_import_per_cf) {
         const auto s =
             fs_->DeleteFile(f.internal_file_path, IOOptions(), nullptr);
         if (!s.ok()) {
@@ -207,9 +266,11 @@ void ImportColumnFamilyJob::Cleanup(const Status& status) {
                          f.internal_file_path.c_str(), s.ToString().c_str());
         }
       }
+    }
   } else if (status.ok() && import_options_.move_files) {
     // The files were moved and added successfully, remove original file links
-    for (IngestedFileInfo& f : files_to_import_) {
+    for (auto& files_to_import_per_cf : files_to_import_) {
+      for (auto& f : files_to_import_per_cf) {
         const auto s =
             fs_->DeleteFile(f.external_file_path, IOOptions(), nullptr);
         if (!s.ok()) {
@@ -221,6 +282,7 @@ void ImportColumnFamilyJob::Cleanup(const Status& status) {
         }
       }
     }
+  }
 }
 
 Status ImportColumnFamilyJob::GetIngestedFileInfo(

db/import_column_family_job.h

@@ -25,12 +25,21 @@ class SystemClock;
 // Imports a set of sst files as is into a new column family. Logic is similar
 // to ExternalSstFileIngestionJob.
 class ImportColumnFamilyJob {
+  // All file information of an imported CF, mainly used to
+  // calculate whether there is overlap between CFs
+  struct ColumnFamilyIngestFileInfo {
+    // Smallest internal key in cf
+    InternalKey smallest_internal_key;
+    // Largest internal key in cf
+    InternalKey largest_internal_key;
+  };
+
  public:
-  ImportColumnFamilyJob(VersionSet* versions, ColumnFamilyData* cfd,
-                        const ImmutableDBOptions& db_options,
-                        const EnvOptions& env_options,
+  ImportColumnFamilyJob(
+      VersionSet* versions, ColumnFamilyData* cfd,
+      const ImmutableDBOptions& db_options, const EnvOptions& env_options,
       const ImportColumnFamilyOptions& import_options,
-                        const std::vector<LiveFileMetaData>& metadata,
+      const std::vector<std::vector<LiveFileMetaData*>>& metadatas,
       const std::shared_ptr<IOTracer>& io_tracer)
       : clock_(db_options.clock),
         versions_(versions),
@@ -39,7 +48,7 @@ class ImportColumnFamilyJob {
         fs_(db_options_.fs, io_tracer),
         env_options_(env_options),
         import_options_(import_options),
-        metadata_(metadata),
+        metadatas_(metadatas),
         io_tracer_(io_tracer) {}
 
   // Prepare the job by copying external files into the DB.
@@ -54,7 +63,7 @@ class ImportColumnFamilyJob {
 
   VersionEdit* edit() { return &edit_; }
 
-  const autovector<IngestedFileInfo>& files_to_import() const {
+  const std::vector<std::vector<IngestedFileInfo>>& files_to_import() const {
     return files_to_import_;
   }
 
@@ -72,10 +81,10 @@ class ImportColumnFamilyJob {
   const ImmutableDBOptions& db_options_;
   const FileSystemPtr fs_;
   const EnvOptions& env_options_;
-  autovector<IngestedFileInfo> files_to_import_;
+  std::vector<std::vector<IngestedFileInfo>> files_to_import_;
   VersionEdit edit_;
   const ImportColumnFamilyOptions& import_options_;
-  std::vector<LiveFileMetaData> metadata_;
+  const std::vector<std::vector<LiveFileMetaData*>> metadatas_;
   const std::shared_ptr<IOTracer> io_tracer_;
 };
 

db/import_column_family_test.cc

@@ -22,10 +22,13 @@ class ImportColumnFamilyTest : public DBTestBase {
       : DBTestBase("import_column_family_test", /*env_do_fsync=*/true) {
     sst_files_dir_ = dbname_ + "/sst_files/";
     export_files_dir_ = test::PerThreadDBPath(env_, "export");
+    export_files_dir2_ = test::PerThreadDBPath(env_, "export2");
+
     DestroyAndRecreateExternalSSTFilesDir();
     import_cfh_ = nullptr;
     import_cfh2_ = nullptr;
     metadata_ptr_ = nullptr;
+    metadata_ptr2_ = nullptr;
   }
 
   ~ImportColumnFamilyTest() {
@@ -43,14 +46,21 @@ class ImportColumnFamilyTest : public DBTestBase {
       delete metadata_ptr_;
       metadata_ptr_ = nullptr;
     }
+
+    if (metadata_ptr2_) {
+      delete metadata_ptr2_;
+      metadata_ptr2_ = nullptr;
+    }
     EXPECT_OK(DestroyDir(env_, sst_files_dir_));
     EXPECT_OK(DestroyDir(env_, export_files_dir_));
+    EXPECT_OK(DestroyDir(env_, export_files_dir2_));
   }
 
   void DestroyAndRecreateExternalSSTFilesDir() {
     EXPECT_OK(DestroyDir(env_, sst_files_dir_));
     EXPECT_OK(env_->CreateDir(sst_files_dir_));
     EXPECT_OK(DestroyDir(env_, export_files_dir_));
+    EXPECT_OK(DestroyDir(env_, export_files_dir2_));
   }
 
   LiveFileMetaData LiveFileMetaDataInit(std::string name, std::string path,
@@ -69,9 +79,11 @@ class ImportColumnFamilyTest : public DBTestBase {
  protected:
   std::string sst_files_dir_;
   std::string export_files_dir_;
+  std::string export_files_dir2_;
   ColumnFamilyHandle* import_cfh_;
   ColumnFamilyHandle* import_cfh2_;
   ExportImportFilesMetaData* metadata_ptr_;
+  ExportImportFilesMetaData* metadata_ptr2_;
 };
 
 TEST_F(ImportColumnFamilyTest, ImportSSTFileWriterFiles) {
@@ -738,6 +750,137 @@ TEST_F(ImportColumnFamilyTest, ImportColumnFamilyNegativeTest) {
   }
 }
 
+TEST_F(ImportColumnFamilyTest, ImportMultiColumnFamilyTest) {
+  Options options = CurrentOptions();
+  CreateAndReopenWithCF({"koko"}, options);
+
+  for (int i = 0; i < 100; ++i) {
+    ASSERT_OK(Put(1, Key(i), Key(i) + "_val"));
+  }
+  ASSERT_OK(Flush(1));
+
+  ASSERT_OK(
+      db_->CompactRange(CompactRangeOptions(), handles_[1], nullptr, nullptr));
+
+  // Overwrite the value in the same set of keys.
+  for (int i = 0; i < 100; ++i) {
+    ASSERT_OK(Put(1, Key(i), Key(i) + "_overwrite"));
+  }
+
+  // Flush again to create another L0 file. It should have higher sequencer.
+  ASSERT_OK(Flush(1));
+
+  Checkpoint* checkpoint1;
+  Checkpoint* checkpoint2;
+  ASSERT_OK(Checkpoint::Create(db_, &checkpoint1));
+  ASSERT_OK(checkpoint1->ExportColumnFamily(handles_[1], export_files_dir_,
+                                            &metadata_ptr_));
+
+  // Create a new db and import the files.
+  DB* db_copy;
+  ASSERT_OK(DestroyDir(env_, dbname_ + "/db_copy"));
+  ASSERT_OK(DB::Open(options, dbname_ + "/db_copy", &db_copy));
+  ColumnFamilyHandle* copy_cfh = nullptr;
+  ASSERT_OK(db_copy->CreateColumnFamily(options, "koko", &copy_cfh));
+  WriteOptions wo;
+  for (int i = 100; i < 200; ++i) {
+    ASSERT_OK(db_copy->Put(wo, copy_cfh, Key(i), Key(i) + "_val"));
+  }
+  ASSERT_OK(db_copy->Flush(FlushOptions()));
+  for (int i = 100; i < 200; ++i) {
+    ASSERT_OK(db_copy->Put(wo, copy_cfh, Key(i), Key(i) + "_overwrite"));
+  }
+  ASSERT_OK(db_copy->Flush(FlushOptions()));
+  for (int i = 100; i < 200; ++i) {
+    ASSERT_OK(db_copy->Put(wo, copy_cfh, Key(i), Key(i) + "_overwrite2"));
+  }
+  ASSERT_OK(db_copy->Flush(FlushOptions()));
+
+  // Flush again to create another L0 file. It should have higher sequencer.
+  ASSERT_OK(Checkpoint::Create(db_copy, &checkpoint2));
+  ASSERT_OK(checkpoint2->ExportColumnFamily(copy_cfh, export_files_dir2_,
+                                            &metadata_ptr2_));
+
+  ASSERT_NE(metadata_ptr_, nullptr);
+  ASSERT_NE(metadata_ptr2_, nullptr);
+  delete checkpoint1;
+  delete checkpoint2;
+  ImportColumnFamilyOptions import_options;
+  import_options.move_files = false;
+
+  std::vector<const ExportImportFilesMetaData*> metadatas = {metadata_ptr_,
+                                                             metadata_ptr2_};
+  ASSERT_OK(db_->CreateColumnFamilyWithImport(options, "toto", import_options,
+                                              metadatas, &import_cfh_));
+
+  std::string value1, value2;
+  for (int i = 0; i < 100; ++i) {
+    ASSERT_OK(db_->Get(ReadOptions(), import_cfh_, Key(i), &value1));
+    ASSERT_EQ(Get(1, Key(i)), value1);
+  }
+
+  for (int i = 100; i < 200; ++i) {
+    ASSERT_OK(db_->Get(ReadOptions(), import_cfh_, Key(i), &value1));
+    ASSERT_OK(db_copy->Get(ReadOptions(), copy_cfh, Key(i), &value2));
+    ASSERT_EQ(value1, value2);
+  }
+
+  ASSERT_OK(db_copy->DropColumnFamily(copy_cfh));
+  ASSERT_OK(db_copy->DestroyColumnFamilyHandle(copy_cfh));
+  delete db_copy;
+  ASSERT_OK(DestroyDir(env_, dbname_ + "/db_copy"));
+}
+
+TEST_F(ImportColumnFamilyTest, ImportMultiColumnFamilyWithOverlap) {
+  Options options = CurrentOptions();
+  CreateAndReopenWithCF({"koko"}, options);
+
+  for (int i = 0; i < 100; ++i) {
+    ASSERT_OK(Put(1, Key(i), Key(i) + "_val"));
+  }
+
+  Checkpoint* checkpoint1;
+  Checkpoint* checkpoint2;
+  ASSERT_OK(Checkpoint::Create(db_, &checkpoint1));
+  ASSERT_OK(checkpoint1->ExportColumnFamily(handles_[1], export_files_dir_,
+                                            &metadata_ptr_));
+
+  // Create a new db and import the files.
+  DB* db_copy;
+  ASSERT_OK(DestroyDir(env_, dbname_ + "/db_copy"));
+  ASSERT_OK(DB::Open(options, dbname_ + "/db_copy", &db_copy));
+  ColumnFamilyHandle* copy_cfh = nullptr;
+  ASSERT_OK(db_copy->CreateColumnFamily(options, "koko", &copy_cfh));
+  WriteOptions wo;
+  for (int i = 50; i < 150; ++i) {
+    ASSERT_OK(db_copy->Put(wo, copy_cfh, Key(i), Key(i) + "_val"));
+  }
+  ASSERT_OK(db_copy->Flush(FlushOptions()));
+
+  // Flush again to create another L0 file. It should have higher sequencer.
+  ASSERT_OK(Checkpoint::Create(db_copy, &checkpoint2));
+  ASSERT_OK(checkpoint2->ExportColumnFamily(copy_cfh, export_files_dir2_,
+                                            &metadata_ptr2_));
+
+  ASSERT_NE(metadata_ptr_, nullptr);
+  ASSERT_NE(metadata_ptr2_, nullptr);
+  delete checkpoint1;
+  delete checkpoint2;
+  ImportColumnFamilyOptions import_options;
+  import_options.move_files = false;
+
+  std::vector<const ExportImportFilesMetaData*> metadatas = {metadata_ptr_,
+                                                             metadata_ptr2_};
+
+  ASSERT_EQ(db_->CreateColumnFamilyWithImport(options, "toto", import_options,
+                                              metadatas, &import_cfh_),
+            Status::InvalidArgument("CFs have overlapping ranges"));
+
+  ASSERT_OK(db_copy->DropColumnFamily(copy_cfh));
+  ASSERT_OK(db_copy->DestroyColumnFamilyHandle(copy_cfh));
+  delete db_copy;
+  ASSERT_OK(DestroyDir(env_, dbname_ + "/db_copy"));
+}
 }  // namespace ROCKSDB_NAMESPACE
 
 int main(int argc, char** argv) {

include/rocksdb/db.h

@@ -1782,14 +1782,27 @@ class DB {
   virtual Status CreateColumnFamilyWithImport(
       const ColumnFamilyOptions& options, const std::string& column_family_name,
       const ImportColumnFamilyOptions& import_options,
-      const ExportImportFilesMetaData& metadata,
+      const ExportImportFilesMetaData& metadata, ColumnFamilyHandle** handle) {
+    const std::vector<const ExportImportFilesMetaData*>& metadatas{&metadata};
+    return CreateColumnFamilyWithImport(options, column_family_name,
+                                        import_options, metadatas, handle);
+  }
+
+  // EXPERIMENTAL
+  // Overload of the CreateColumnFamilyWithImport() that allows the caller to
+  // pass a list of ExportImportFilesMetaData pointers to support creating
+  // ColumnFamily by importing multiple ColumnFamilies.
+  // It should be noticed that if the user keys of the imported column families
+  // overlap with each other, an error will be returned.
+  virtual Status CreateColumnFamilyWithImport(
+      const ColumnFamilyOptions& options, const std::string& column_family_name,
+      const ImportColumnFamilyOptions& import_options,
+      const std::vector<const ExportImportFilesMetaData*>& metadatas,
       ColumnFamilyHandle** handle) = 0;
 
   // EXPERIMENTAL
   // ClipColumnFamily() will clip the entries in the CF according to the range
-  // [begin_key,
-  // end_key).
-  // Returns OK on success, and a non-OK status on error.
+  // [begin_key, end_key). Returns OK on success, and a non-OK status on error.
   // Any entries outside this range will be completely deleted (including
   // tombstones).
   // The main difference between ClipColumnFamily(begin, end) and
@@ -1797,8 +1810,7 @@ class DB {
   // is that the former physically deletes all keys outside the range, but is
   // more heavyweight than the latter.
   // This feature is mainly used to ensure that there is no overlapping Key when
-  // calling
-  // CreateColumnFamilyWithImports() to import multiple CFs.
+  // calling CreateColumnFamilyWithImport() to import multiple CFs.
   // Note that: concurrent updates cannot be performed during Clip.
   virtual Status ClipColumnFamily(ColumnFamilyHandle* column_family,
                                   const Slice& begin_key,

include/rocksdb/utilities/stackable_db.h

@@ -172,10 +172,10 @@ class StackableDB : public DB {
   virtual Status CreateColumnFamilyWithImport(
       const ColumnFamilyOptions& options, const std::string& column_family_name,
       const ImportColumnFamilyOptions& import_options,
-      const ExportImportFilesMetaData& metadata,
+      const std::vector<const ExportImportFilesMetaData*>& metadatas,
       ColumnFamilyHandle** handle) override {
     return db_->CreateColumnFamilyWithImport(options, column_family_name,
-                                             import_options, metadata, handle);
+                                             import_options, metadatas, handle);
   }
 
   using DB::ClipColumnFamily;

unreleased_history/public_api_changes/support_create_cf_with_import_multiple_cf.md

@@ -0,0 +1 @@
+Overload the API CreateColumnFamilyWithImport() to support creating ColumnFamily by importing multiple ColumnFamilies It requires that CFs should not overlap in user key range.