From d91380cd712bb1fbb1c8e0878f8114329344d7e6 Mon Sep 17 00:00:00 2001
From: alesapin <alesapin@gmail.com>
Date: Wed, 28 Jul 2021 15:04:42 +0300
Subject: [PATCH] Fix bug when default column reference non materialized column

---
 src/Interpreters/inplaceBlockConversions.cpp    | 10 ++++++++++
 ..._default_from_default_empty_column.reference |  1 +
 .../02000_default_from_default_empty_column.sql | 17 +++++++++++++++++
 3 files changed, 28 insertions(+)
 create mode 100644 tests/queries/0_stateless/02000_default_from_default_empty_column.reference
 create mode 100644 tests/queries/0_stateless/02000_default_from_default_empty_column.sql

diff --git a/src/Interpreters/inplaceBlockConversions.cpp b/src/Interpreters/inplaceBlockConversions.cpp
index ff16c7b3ff6..26cf6912bc7 100644
--- a/src/Interpreters/inplaceBlockConversions.cpp
+++ b/src/Interpreters/inplaceBlockConversions.cpp
@@ -53,6 +53,7 @@ void addDefaultRequiredExpressionsRecursively(
         NameSet required_columns_names = columns_context.requiredColumns();
 
         auto expr = makeASTFunction("CAST", column_default_expr, std::make_shared<ASTLiteral>(columns.get(required_column_name).type->getName()));
+
         if (is_column_in_query && convert_null_to_default)
             expr = makeASTFunction("ifNull", std::make_shared<ASTIdentifier>(required_column_name), std::move(expr));
         default_expr_list_accum->children.emplace_back(setAlias(expr, required_column_name));
@@ -62,6 +63,15 @@ void addDefaultRequiredExpressionsRecursively(
         for (const auto & next_required_column_name : required_columns_names)
             addDefaultRequiredExpressionsRecursively(block, next_required_column_name, required_column_type, columns, default_expr_list_accum, added_columns, null_as_default);
     }
+    else
+    {
+        /// This column is required, but doesn't have default expression, so lets use "default default"
+        auto column = columns.get(required_column_name);
+        auto default_value = column.type->getDefault();
+        auto default_ast = std::make_shared<ASTLiteral>(default_value);
+        default_expr_list_accum->children.emplace_back(setAlias(default_ast, required_column_name));
+        added_columns.emplace(required_column_name);
+    }
 }
 
 ASTPtr defaultRequiredExpressions(const Block & block, const NamesAndTypesList & required_columns, const ColumnsDescription & columns, bool null_as_default)
diff --git a/tests/queries/0_stateless/02000_default_from_default_empty_column.reference b/tests/queries/0_stateless/02000_default_from_default_empty_column.reference
new file mode 100644
index 00000000000..bb48d0eda85
--- /dev/null
+++ b/tests/queries/0_stateless/02000_default_from_default_empty_column.reference
@@ -0,0 +1 @@
+1		
diff --git a/tests/queries/0_stateless/02000_default_from_default_empty_column.sql b/tests/queries/0_stateless/02000_default_from_default_empty_column.sql
new file mode 100644
index 00000000000..5ca642628d4
--- /dev/null
+++ b/tests/queries/0_stateless/02000_default_from_default_empty_column.sql
@@ -0,0 +1,17 @@
+DROP TABLE IF EXISTS test;
+
+CREATE TABLE test (col Int8) ENGINE=MergeTree ORDER BY tuple()
+SETTINGS vertical_merge_algorithm_min_rows_to_activate=1,
+         vertical_merge_algorithm_min_columns_to_activate=1,
+         min_bytes_for_wide_part = 0;
+
+
+INSERT INTO test VALUES (1);
+ALTER TABLE test ADD COLUMN s1 String;
+ALTER TABLE test ADD COLUMN s2 String DEFAULT s1;
+
+OPTIMIZE TABLE test FINAL;
+
+SELECT * FROM test;
+
+DROP TABLE IF EXISTS test;