Add serialization for LimitByStep.

src/Processors/QueryPlan/LimitByStep.cpp

@@ -1,4 +1,5 @@
 #include <Processors/QueryPlan/LimitByStep.h>
+#include <Processors/QueryPlan/QueryPlanStepRegistry.h>
 #include <Processors/Transforms/LimitByTransform.h>
 #include <QueryPipeline/QueryPipelineBuilder.h>
 #include <IO/Operators.h>
@@ -24,11 +25,11 @@ static ITransformingStep::Traits getTraits()
 
 LimitByStep::LimitByStep(
     const DataStream & input_stream_,
-    size_t group_length_, size_t group_offset_, const Names & columns_)
+    size_t group_length_, size_t group_offset_, Names columns_)
     : ITransformingStep(input_stream_, input_stream_.header, getTraits())
     , group_length(group_length_)
     , group_offset(group_offset_)
-    , columns(columns_)
+    , columns(std::move(columns_))
 {
 }
 
@@ -83,4 +84,38 @@ void LimitByStep::describeActions(JSONBuilder::JSONMap & map) const
     map.add("Offset", group_offset);
 }
 
+void LimitByStep::serialize(WriteBuffer & out) const
+{
+    writeVarUInt(group_length, out);
+    writeVarUInt(group_offset, out);
+
+
+    writeVarUInt(columns.size(), out);
+    for (const auto & column : columns)
+        writeStringBinary(column, out);
+}
+
+std::unique_ptr<IQueryPlanStep> LimitByStep::deserialize(
+    ReadBuffer & in, const DataStreams & input_streams_, const DataStream *, QueryPlanSerializationSettings &)
+{
+    UInt64 group_length;
+    UInt64 group_offset;
+
+    readVarUInt(group_length, in);
+    readVarUInt(group_offset, in);
+
+    UInt64 num_columns;
+    readVarUInt(num_columns, in);
+    Names columns(num_columns);
+    for (auto & column : columns)
+        readStringBinary(column, in);
+
+    return std::make_unique<LimitByStep>(input_streams_.front(), group_length, group_offset, std::move(columns));
+}
+
+void registerLimitByStep(QueryPlanStepRegistry & registry)
+{
+    registry.registerStep("LimitBy", LimitByStep::deserialize);
+}
+
 }

src/Processors/QueryPlan/LimitByStep.h

@@ -10,7 +10,7 @@ class LimitByStep : public ITransformingStep
 public:
     explicit LimitByStep(
             const DataStream & input_stream_,
-            size_t group_length_, size_t group_offset_, const Names & columns_);
+            size_t group_length_, size_t group_offset_, Names columns_);
 
     String getName() const override { return "LimitBy"; }
 
@@ -19,6 +19,10 @@ public:
     void describeActions(JSONBuilder::JSONMap & map) const override;
     void describeActions(FormatSettings & settings) const override;
 
+    void serialize(WriteBuffer & out) const override;
+
+    static std::unique_ptr<IQueryPlanStep> deserialize(ReadBuffer & in, const DataStreams & input_streams_, const DataStream *, QueryPlanSerializationSettings &);
+
 private:
     void updateOutputStream() override
     {

src/Processors/QueryPlan/QueryPlanStepRegistry.cpp

@@ -45,6 +45,7 @@ void registerDistinctStep(QueryPlanStepRegistry & registry);
 void registerSortingStep(QueryPlanStepRegistry & registry);
 void registerAggregatingStep(QueryPlanStepRegistry & registry);
 void registerArrayJoinStep(QueryPlanStepRegistry & registry);
+void registerLimitByStep(QueryPlanStepRegistry & registry);
 
 void registerReadFromTableStep(QueryPlanStepRegistry & registry);
 
@@ -58,6 +59,7 @@ void QueryPlanStepRegistry::registerPlanSteps()
     registerSortingStep(registry);
     registerAggregatingStep(registry);
     registerArrayJoinStep(registry);
+    registerLimitByStep(registry);
 
     registerReadFromTableStep(registry);
 }