Fixed test [#CLICKHOUSE-2]

dbms/src/Storages/StorageBuffer.cpp

@@ -323,6 +323,20 @@ BlockOutputStreamPtr StorageBuffer::write(const ASTPtr & /*query*/, const Settin
 }
 
 
+bool StorageBuffer::mayBenefitFromIndexForIn(const ASTPtr & left_in_operand) const
+{
+    if (no_destination)
+        return false;
+
+    auto destination = context.getTable(destination_database, destination_table);
+
+    if (destination.get() == this)
+        throw Exception("Destination table is myself. Read will cause infinite loop.", ErrorCodes::INFINITE_LOOP);
+
+    return destination->mayBenefitFromIndexForIn(left_in_operand);
+}
+
+
 void StorageBuffer::startup()
 {
     if (context.getSettingsRef().readonly)

dbms/src/Storages/StorageBuffer.h

@@ -75,6 +75,8 @@ public:
     bool supportsFinal() const override { return true; }
     bool supportsIndexForIn() const override { return true; }
 
+    bool mayBenefitFromIndexForIn(const ASTPtr & left_in_operand) const override;
+
     /// The structure of the subordinate table is not checked and does not change.
     void alter(const AlterCommands & params, const String & database_name, const String & table_name, const Context & context) override;
 

dbms/src/Storages/StorageMerge.cpp

@@ -111,6 +111,27 @@ namespace
 }
 
 
+bool StorageMerge::mayBenefitFromIndexForIn(const ASTPtr & left_in_operand) const
+{
+    /// It's beneficial if it is true for at least one table.
+    StorageListWithLocks selected_tables = getSelectedTables();
+
+    size_t i = 0;
+    for (const auto & table : selected_tables)
+    {
+        if (table.first->mayBenefitFromIndexForIn(left_in_operand))
+            return true;
+
+        ++i;
+        /// For simplicity reasons, check only first ten tables.
+        if (i > 10)
+            break;
+    }
+
+    return false;
+}
+
+
 BlockInputStreams StorageMerge::read(
     const Names & column_names,
     const SelectQueryInfo & query_info,

dbms/src/Storages/StorageMerge.h

@@ -44,6 +44,8 @@ public:
     /// the structure of sub-tables is not checked
     void alter(const AlterCommands & params, const String & database_name, const String & table_name, const Context & context) override;
 
+    bool mayBenefitFromIndexForIn(const ASTPtr & left_in_operand) const override;
+
 private:
     String name;
     String source_database;