fix #2768 (#2809)

* fix #2752
Signed-off-by: Nyhmo <yihua.mo@zilliz.com>

* typo
Signed-off-by: Nyhmo <yihua.mo@zilliz.com>

* typo
Signed-off-by: Nyhmo <yihua.mo@zilliz.com>

* fix #2768
Signed-off-by: Nyhmo <yihua.mo@zilliz.com>

* typo
Signed-off-by: Nyhmo <yihua.mo@zilliz.com>

* typo
Signed-off-by: Ngroot <yihua.mo@zilliz.com>

* typo again
Signed-off-by: Ngroot <yihua.mo@zilliz.com>

CHANGELOG.md

@@ -18,7 +18,8 @@ Please mark all change in change log and use the issue from GitHub
 -   \#2692 Milvus hangs during multi-thread concurrent search
 -   \#2739 Fix mishards start failed
 -   \#2752 Milvus formats vectors data to double-precision and return to http client
--   \#2767 fix a bug of getting wrong nprobe limitation in knowhere on GPU version
+-   \#2767 Fix a bug of getting wrong nprobe limitation in knowhere on GPU version
+-   \#2768 After building the index,the number of vectors increases
 -   \#2776 Fix too many data copies during creating IVF index
 
 ## Feature

core/src/db/DBImpl.cpp

@@ -2390,7 +2390,7 @@ DBImpl::GetPartitionsByTags(const std::string& collection_id, const std::vector<
 Status
 DBImpl::UpdateCollectionIndexRecursively(const std::string& collection_id, const CollectionIndex& index) {
     DropIndex(collection_id);
-
+    WaitMergeFileFinish();  // DropIndex called StartMergeTask, need to wait merge thread finish
     auto status = meta_ptr_->UpdateCollectionIndex(collection_id, index);
     fiu_do_on("DBImpl.UpdateCollectionIndexRecursively.fail_update_collection_index",
               status = Status(DB_META_TRANSACTION_FAILED, ""));