add type conversion

Author: filimonov

src/Storages/StorageDistributed.cpp

@@ -9,6 +9,7 @@
 #include <Processors/QueryPlan/QueryPlan.h>
 #include <Processors/QueryPlan/SourceStepWithFilter.h>
 #include <Processors/QueryPlan/Optimizations/QueryPlanOptimizationSettings.h>
+#include <Processors/QueryPlan/ConvertingActions.h>
 #include <Interpreters/InterpreterSelectQueryAnalyzer.h>
 #include <Interpreters/InterpreterSelectWithUnionQuery.h>
 #include <IO/WriteBufferFromString.h>
@@ -1225,10 +1226,19 @@ void StorageDistributed::read(
             plan_ptrs.push_back(std::make_unique<QueryPlan>(std::move(plan)));
         }
 
+        // Get the main plan's header to use as the target for type conversion
+        Block main_header = plan_ptrs[0]->getCurrentHeader();
+
+        // Add type conversion for each additional plan to match the main plan's header
+        for (size_t i = 1; i < plan_ptrs.size(); ++i)
+        {
+            addConvertingActions(*plan_ptrs[i], main_header, false);
+        }
+
         // Create a new query plan that unions all the results
         QueryPlan union_plan;
 
-        // Get headers from all plans
+        // Get headers from all plans (after conversion)
         std::vector<Block> headers;
         headers.reserve(plan_ptrs.size());
         for (const auto & plan_ptr : plan_ptrs)