From c642e16ee1ac3a5c9986c898e5d8c58c4e705bb7 Mon Sep 17 00:00:00 2001
From: chertus <chertus@gmail.com>
Date: Thu, 15 Nov 2018 19:57:20 +0300
Subject: [PATCH] clearer evaluateMissingDefaults [CLICKHOUSE-3578]

---
 .../AddingDefaultsBlockInputStream.cpp        |  2 +-
 dbms/src/DataStreams/IBlockInputStream.h      |  1 -
 .../Interpreters/evaluateMissingDefaults.cpp  | 42 ++++++-------------
 .../Interpreters/evaluateMissingDefaults.h    |  7 +---
 4 files changed, 14 insertions(+), 38 deletions(-)

diff --git a/dbms/src/DataStreams/AddingDefaultsBlockInputStream.cpp b/dbms/src/DataStreams/AddingDefaultsBlockInputStream.cpp
index 900a923b23a..3d02b0c6415 100644
--- a/dbms/src/DataStreams/AddingDefaultsBlockInputStream.cpp
+++ b/dbms/src/DataStreams/AddingDefaultsBlockInputStream.cpp
@@ -49,7 +49,7 @@ Block AddingDefaultsBlockInputStream::readImpl()
             evaluate_block.erase(column.first);
     }
 
-    evaluateMissingDefaultsUnsafe(evaluate_block, header.getNamesAndTypesList(), column_defaults, context);
+    evaluateMissingDefaults(evaluate_block, header.getNamesAndTypesList(), column_defaults, context, false);
 
     std::unordered_map<size_t, MutableColumnPtr> mixed_columns;
 
diff --git a/dbms/src/DataStreams/IBlockInputStream.h b/dbms/src/DataStreams/IBlockInputStream.h
index 2e305b4b451..eb5f75ef46c 100644
--- a/dbms/src/DataStreams/IBlockInputStream.h
+++ b/dbms/src/DataStreams/IBlockInputStream.h
@@ -19,7 +19,6 @@ class IBlockInputStream;
 using BlockInputStreamPtr = std::shared_ptr<IBlockInputStream>;
 using BlockInputStreams = std::vector<BlockInputStreamPtr>;
 
-class BlockMissingValues;
 class TableStructureReadLock;
 
 using TableStructureReadLockPtr = std::shared_ptr<TableStructureReadLock>;
diff --git a/dbms/src/Interpreters/evaluateMissingDefaults.cpp b/dbms/src/Interpreters/evaluateMissingDefaults.cpp
index 8d84c8f6576..40b75c0b673 100644
--- a/dbms/src/Interpreters/evaluateMissingDefaults.cpp
+++ b/dbms/src/Interpreters/evaluateMissingDefaults.cpp
@@ -29,33 +29,36 @@ static ASTPtr requiredExpressions(Block & block, const NamesAndTypesList & requi
                 setAlias(it->second.expression->clone(), it->first));
     }
 
+    if (default_expr_list->children.empty())
+        return nullptr;
     return default_expr_list;
 }
 
-
 void evaluateMissingDefaults(Block & block,
     const NamesAndTypesList & required_columns,
     const ColumnDefaults & column_defaults,
-    const Context & context)
+    const Context & context, bool with_block_copy)
 {
     if (column_defaults.empty())
         return;
 
     ASTPtr default_expr_list = requiredExpressions(block, required_columns, column_defaults);
-    /// nothing to evaluate
-    if (default_expr_list->children.empty())
+    if (!default_expr_list)
         return;
 
+    if (!with_block_copy)
+    {
+        auto syntax_result = SyntaxAnalyzer(context, {}).analyze(default_expr_list, block.getNamesAndTypesList());
+        ExpressionAnalyzer{default_expr_list, syntax_result, context}.getActions(true)->execute(block);
+        return;
+    }
+
     /** ExpressionAnalyzer eliminates "unused" columns, in order to ensure their safety
       * we are going to operate on a copy instead of the original block */
     Block copy_block{block};
     /// evaluate default values for defaulted columns
 
-    NamesAndTypesList available_columns;
-    for (size_t i = 0, size = block.columns(); i < size; ++i)
-        available_columns.emplace_back(block.getByPosition(i).name, block.getByPosition(i).type);
-
-    auto syntax_result = SyntaxAnalyzer(context, {}).analyze(default_expr_list, available_columns);
+    auto syntax_result = SyntaxAnalyzer(context, {}).analyze(default_expr_list, block.getNamesAndTypesList());
     ExpressionAnalyzer{default_expr_list, syntax_result, context}.getActions(true)->execute(copy_block);
 
     /// move evaluated columns to the original block, materializing them at the same time
@@ -73,25 +76,4 @@ void evaluateMissingDefaults(Block & block,
     }
 }
 
-
-void evaluateMissingDefaultsUnsafe(Block & block,
-    const NamesAndTypesList & required_columns,
-    const std::unordered_map<std::string, ColumnDefault> & column_defaults,
-    const Context & context)
-{
-    if (column_defaults.empty())
-        return;
-
-    ASTPtr default_expr_list = requiredExpressions(block, required_columns, column_defaults);
-    if (default_expr_list->children.empty())
-        return;
-
-    NamesAndTypesList available_columns;
-    for (size_t i = 0, size = block.columns(); i < size; ++i)
-        available_columns.emplace_back(block.getByPosition(i).name, block.getByPosition(i).type);
-
-    auto syntax_result = SyntaxAnalyzer(context, {}).analyze(default_expr_list, available_columns);
-    ExpressionAnalyzer{default_expr_list, syntax_result, context}.getActions(true)->execute(block);
-}
-
 }
diff --git a/dbms/src/Interpreters/evaluateMissingDefaults.h b/dbms/src/Interpreters/evaluateMissingDefaults.h
index ce0c649f3d0..71f6fab9753 100644
--- a/dbms/src/Interpreters/evaluateMissingDefaults.h
+++ b/dbms/src/Interpreters/evaluateMissingDefaults.h
@@ -15,11 +15,6 @@ struct ColumnDefault;
 void evaluateMissingDefaults(Block & block,
     const NamesAndTypesList & required_columns,
     const std::unordered_map<std::string, ColumnDefault> & column_defaults,
-    const Context & context);
-
-void evaluateMissingDefaultsUnsafe(Block & block,
-    const NamesAndTypesList & required_columns,
-    const std::unordered_map<std::string, ColumnDefault> & column_defaults,
-    const Context & context);
+    const Context & context, bool with_block_copy = true);
 
 }