From e6d8ab2270532e3ed5171d9ee1e8b52ca2843f82 Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@yandex-team.ru>
Date: Mon, 2 Nov 2020 21:37:23 +0300
Subject: [PATCH] Fix possible name collision in ALTER

---
 src/Interpreters/InterpreterCreateQuery.cpp              | 3 ++-
 src/Storages/AlterCommands.cpp                           | 9 ++++-----
 .../0_stateless/01552_alter_name_collision.reference     | 0
 tests/queries/0_stateless/01552_alter_name_collision.sql | 3 +++
 4 files changed, 9 insertions(+), 6 deletions(-)
 create mode 100644 tests/queries/0_stateless/01552_alter_name_collision.reference
 create mode 100644 tests/queries/0_stateless/01552_alter_name_collision.sql

diff --git a/src/Interpreters/InterpreterCreateQuery.cpp b/src/Interpreters/InterpreterCreateQuery.cpp
index ddb1d738031..6a8bdbea1ec 100644
--- a/src/Interpreters/InterpreterCreateQuery.cpp
+++ b/src/Interpreters/InterpreterCreateQuery.cpp
@@ -6,6 +6,7 @@
 #include <Common/escapeForFileName.h>
 #include <Common/typeid_cast.h>
 #include <Common/Macros.h>
+#include <Common/randomSeed.h>
 
 #include <Core/Defines.h>
 #include <Core/Settings.h>
@@ -362,7 +363,7 @@ ColumnsDescription InterpreterCreateQuery::getColumnsDescription(
             if (col_decl.type)
             {
                 const auto & final_column_name = col_decl.name;
-                const auto tmp_column_name = final_column_name + "_tmp";
+                const auto tmp_column_name = final_column_name + "_tmp_alter" + toString(randomSeed());
                 const auto * data_type_ptr = column_names_and_types.back().type.get();
 
                 default_expr_list->children.emplace_back(
diff --git a/src/Storages/AlterCommands.cpp b/src/Storages/AlterCommands.cpp
index 8cae7866748..559121d6911 100644
--- a/src/Storages/AlterCommands.cpp
+++ b/src/Storages/AlterCommands.cpp
@@ -22,12 +22,11 @@
 #include <Parsers/ASTIndexDeclaration.h>
 #include <Parsers/ASTLiteral.h>
 #include <Parsers/ASTSetQuery.h>
+#include <Parsers/queryToString.h>
 #include <Storages/AlterCommands.h>
 #include <Storages/IStorage.h>
 #include <Common/typeid_cast.h>
-
-
-#include <Parsers/queryToString.h>
+#include <Common/randomSeed.h>
 
 
 namespace DB
@@ -1117,7 +1116,7 @@ void AlterCommands::validate(const StorageInMemoryMetadata & metadata, const Con
                     data_type_ptr = command.data_type;
 
                 const auto & final_column_name = column_name;
-                const auto tmp_column_name = final_column_name + "_tmp";
+                const auto tmp_column_name = final_column_name + "_tmp_alter" + toString(randomSeed());
 
                 default_expr_list->children.emplace_back(setAlias(
                     addTypeConversionToAST(std::make_shared<ASTIdentifier>(tmp_column_name), data_type_ptr->getName()),
@@ -1133,7 +1132,7 @@ void AlterCommands::validate(const StorageInMemoryMetadata & metadata, const Con
                     continue;
 
                 const auto & final_column_name = column_name;
-                const auto tmp_column_name = final_column_name + "_tmp";
+                const auto tmp_column_name = final_column_name + "_tmp_alter" + toString(randomSeed());
                 const auto data_type_ptr = command.data_type;
 
                 default_expr_list->children.emplace_back(setAlias(
diff --git a/tests/queries/0_stateless/01552_alter_name_collision.reference b/tests/queries/0_stateless/01552_alter_name_collision.reference
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/queries/0_stateless/01552_alter_name_collision.sql b/tests/queries/0_stateless/01552_alter_name_collision.sql
new file mode 100644
index 00000000000..dc717f1071a
--- /dev/null
+++ b/tests/queries/0_stateless/01552_alter_name_collision.sql
@@ -0,0 +1,3 @@
+DROP TABLE IF EXISTS test;
+CREATE TABLE test(test String DEFAULT 'test', test_tmp Int DEFAULT 1)ENGINE = Memory;
+DROP TABLE test;