FLASH-479 select from empty table throw error in tiflash

dbms/src/Debug/dbgFuncCoprocessor.cpp

@@ -73,7 +73,7 @@ BlockInputStreamPtr dbgFuncDAG(Context & context, const ASTs & args)
     }
     else
     {
-        region = context.getTMTContext().getRegionTable().getRegionByTableAndID(table_id, region_id);
+        region = context.getTMTContext().getKVStore()->getRegion(region_id);
         if (!region)
             throw Exception("No such region", ErrorCodes::BAD_ARGUMENTS);
     }

dbms/src/Flash/Coprocessor/DAGDriver.cpp

@@ -28,7 +28,8 @@ DAGDriver::DAGDriver(Context & context_, const tipb::DAGRequest & dag_request_,
       region_version(region_version_),
       region_conf_version(region_conf_version_),
       dag_response(dag_response_),
-      internal(internal_)
+      internal(internal_),
+      log(&Logger::get("DAGDriver"))
 {}
 
 void DAGDriver::execute()
@@ -98,10 +99,12 @@ catch (const LockException & e)
 }
 catch (const Exception & e)
 {
+    LOG_ERROR(log, __PRETTY_FUNCTION__ << ": Exception: " << e.displayText());
     recordError(e.code(), e.message());
 }
 catch (const std::exception & e)
 {
+    LOG_ERROR(log, __PRETTY_FUNCTION__ << ": Exception: " << e.what());
     recordError(ErrorCodes::UNKNOWN_EXCEPTION, e.what());
 }
 

dbms/src/Flash/Coprocessor/DAGDriver.h

@@ -32,6 +32,8 @@ class DAGDriver
 
     bool internal;
 
+    Poco::Logger * log;
+
     void recordError(Int32 err_code, const String & err_msg);
 };
 } // namespace DB

dbms/src/Flash/Coprocessor/InterpreterDAG.cpp

@@ -7,6 +7,7 @@
 #include <DataStreams/FilterBlockInputStream.h>
 #include <DataStreams/LimitBlockInputStream.h>
 #include <DataStreams/MergeSortingBlockInputStream.h>
+#include <DataStreams/NullBlockInputStream.h>
 #include <DataStreams/ParallelAggregatingBlockInputStream.h>
 #include <DataStreams/PartialSortingBlockInputStream.h>
 #include <DataStreams/UnionBlockInputStream.h>
@@ -16,6 +17,7 @@
 #include <Parsers/ASTSelectQuery.h>
 #include <Storages/RegionQueryInfo.h>
 #include <Storages/StorageMergeTree.h>
+#include <Storages/Transaction/KVStore.h>
 #include <Storages/Transaction/Region.h>
 #include <Storages/Transaction/RegionException.h>
 #include <Storages/Transaction/SchemaSyncer.h>
@@ -136,7 +138,7 @@ void InterpreterDAG::executeTS(const tipb::TableScan & ts, Pipeline & pipeline)
     info.region_id = dag.getRegionID();
     info.version = dag.getRegionVersion();
     info.conf_version = dag.getRegionConfVersion();
-    auto current_region = context.getTMTContext().getRegionTable().getRegionByTableAndID(table_id, info.region_id);
+    auto current_region = context.getTMTContext().getKVStore()->getRegion(info.region_id);
     if (!current_region)
     {
         std::vector<RegionID> region_ids;
@@ -148,6 +150,11 @@ void InterpreterDAG::executeTS(const tipb::TableScan & ts, Pipeline & pipeline)
     query_info.mvcc_query_info->concurrent = 0.0;
     pipeline.streams = storage->read(required_columns, query_info, context, from_stage, max_block_size, max_streams);
 
+    if (pipeline.streams.empty())
+    {
+        pipeline.streams.emplace_back(std::make_shared<NullBlockInputStream>(storage->getSampleBlockForColumns(required_columns)));
+    }
+
     pipeline.transform([&](auto & stream) { stream->addTableLock(table_lock); });
 
     /// Set the limits and quota for reading data, the speed and time of the query.
@@ -178,7 +185,6 @@ void InterpreterDAG::executeTS(const tipb::TableScan & ts, Pipeline & pipeline)
             }
         });
     }
-    ColumnsWithTypeAndName columnsWithTypeAndName = pipeline.firstStream()->getHeader().getColumnsWithTypeAndName();
 }
 
 InterpreterDAG::AnalysisResult InterpreterDAG::analyzeExpressions()

dbms/src/Storages/Transaction/RegionTable.cpp

@@ -501,24 +501,6 @@ std::vector<std::pair<RegionID, RegionPtr>> RegionTable::getRegionsByTable(const
     return regions;
 }
 
-RegionPtr RegionTable::getRegionByTableAndID(const TableID table_id, const RegionID region_id)
-{
-    auto & kvstore = context.getTMTContext().getKVStore();
-    {
-        std::lock_guard<std::mutex> lock(mutex);
-        auto & table = getOrCreateTable(table_id);
-
-        for (const auto & region_info : table.regions)
-        {
-            if (region_info.second.region_id == region_id)
-            {
-                return kvstore->getRegion(region_info.second.region_id);
-            }
-        }
-    }
-    return nullptr;
-}
-
 void RegionTable::mockDropRegionsInTable(TableID table_id)
 {
     std::lock_guard<std::mutex> lock(mutex);

dbms/src/Storages/Transaction/RegionTable.h

@@ -181,7 +181,6 @@ class RegionTable : private boost::noncopyable
     void traverseInternalRegions(std::function<void(TableID, InternalRegion &)> && callback);
     void traverseInternalRegionsByTable(const TableID table_id, std::function<void(const InternalRegion &)> && callback);
     std::vector<std::pair<RegionID, RegionPtr>> getRegionsByTable(const TableID table_id);
-    RegionPtr getRegionByTableAndID(const TableID table_id, const RegionID region_id);
 
     /// Write the data of the given region into the table with the given table ID, fill the data list for outer to remove.
     /// Will trigger schema sync on read error for only once,