SERVER-66208 Remove chunk creation for shard collection with existing data

Co-authored-by: Kaloian Manassiev <kaloian.manassiev@mongodb.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/src/mongo/db/s/config/initial_split_policy.h b/src/mongo/db/s/config/initial_split_policy.h
index ced8d519a13..ed731ddaea0 100644
--- a/src/mongo/db/s/config/initial_split_policy.h
+++ b/src/mongo/db/s/config/initial_split_policy.h
@@ -53,6 +53,11 @@ public:
     /**
      * Returns the optimization strategy for building initial chunks based on the input parameters
      * and the collection state.
+     *
+     * The 'useAutoSplitter' flag indicates to the initial split strategy selected that in case the
+     * collection contains data, it should use the auto splitter to chop that data into chunks
+     * respective to the configured chunk size. If set to false, the policy will create as large of
+     * chunks as possible.
      */
     static std::unique_ptr<InitialSplitPolicy> calculateOptimizationStrategy(
         OperationContext* opCtx,
@@ -62,7 +67,8 @@ public:
         const boost::optional<std::vector<BSONObj>>& initialSplitPoints,
         const std::vector<TagsType>& tags,
         size_t numShards,
-        bool collectionIsEmpty);
+        bool collectionIsEmpty,
+        bool useAutoSplitter = true /* Controlled by FCV, see the comment */);
 
     virtual ~InitialSplitPolicy() {}
 
@@ -140,7 +146,7 @@ public:
  * Split point building strategy to be used when no optimizations are available. We send a
  * splitVector command to the primary shard in order to calculate the appropriate split points.
  */
-class UnoptimizedSplitPolicy : public InitialSplitPolicy {
+class AutoSplitInChunksOnPrimaryPolicy : public InitialSplitPolicy {
 public:
     ShardCollectionConfig createFirstChunks(OperationContext* opCtx,
                                             const ShardKeyPattern& shardKeyPattern,