From fff1593bd980bd7e3ced1f29d556434408d54856 Mon Sep 17 00:00:00 2001
From: Sergey Fedorov <fets@yandex-team.ru>
Date: Tue, 1 Apr 2014 18:06:58 +0400
Subject: [PATCH] dbms: Sending only required external tables to remote servers
 [METR-10071]

---
 .../DB/Interpreters/ExpressionAnalyzer.h      |  5 ++-
 dbms/src/Interpreters/ExpressionAnalyzer.cpp  | 39 ++++++++++++++++++-
 .../Interpreters/InterpreterSelectQuery.cpp   |  5 ++-
 3 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/dbms/include/DB/Interpreters/ExpressionAnalyzer.h b/dbms/include/DB/Interpreters/ExpressionAnalyzer.h
index 6b22ed29808..c3418bc12d8 100644
--- a/dbms/include/DB/Interpreters/ExpressionAnalyzer.h
+++ b/dbms/include/DB/Interpreters/ExpressionAnalyzer.h
@@ -100,7 +100,7 @@ public:
 	Block getSelectSampleBlock();
 
 	/// Все новые временные таблицы, полученные при выполнении подзапросов GLOBAL IN.
-	std::vector<StoragePtr> external_tables;
+	Tables external_tables;
 private:
 	typedef std::set<String> NamesSet;
 	
@@ -263,7 +263,8 @@ private:
 
 	/// Обходит запрос и сохраняет найденные глобальные функции (например GLOBAL IN)
 	void findGlobalFunctions(ASTPtr & ast, std::vector<ASTPtr> & global_nodes);
-	
+	void findExternalTables(ASTPtr & ast);
+
 	/// Превратить перечисление значений или подзапрос в ASTSet. node - функция in или notIn.
 	void makeSet(ASTFunction * node, const Block & sample_block);
 	/// Выполнить подзапрос в секции GLOBAL IN и запомнить результат во временную таблицу типа memory
diff --git a/dbms/src/Interpreters/ExpressionAnalyzer.cpp b/dbms/src/Interpreters/ExpressionAnalyzer.cpp
index 5c32f4053a4..208bc0c1e9f 100644
--- a/dbms/src/Interpreters/ExpressionAnalyzer.cpp
+++ b/dbms/src/Interpreters/ExpressionAnalyzer.cpp
@@ -516,6 +516,34 @@ void ExpressionAnalyzer::findGlobalFunctions(ASTPtr & ast, std::vector<ASTPtr> &
 }
 
 
+void ExpressionAnalyzer::findExternalTables(ASTPtr & ast)
+{
+	/// Рекурсивные вызовы. Намеренно опускаемся в подзапросы.
+	for (ASTs::iterator it = ast->children.begin(); it != ast->children.end(); ++it)
+		findExternalTables(*it);
+
+	/// Если идентификатор типа таблица
+	StoragePtr external_storage;
+	if (ASTIdentifier * node = dynamic_cast<ASTIdentifier *>(&*ast))
+		if (node->kind == ASTIdentifier::Kind::Table)
+			if (external_storage = context.tryGetExternalTable(node->name))
+				external_tables[node->name] = external_storage;
+
+	if (ASTFunction * node = dynamic_cast<ASTFunction *>(&*ast))
+	{
+		if (node->name == "globalIn" || node->name == "globalNotIn" || node->name == "In" || node->name == "NotIn")
+		{
+			IAST & args = *node->arguments;
+			ASTPtr & arg = args.children[1];
+			/// Если имя таблицы для селекта
+			if (ASTIdentifier * id = dynamic_cast<ASTIdentifier *>(&*arg))
+				if (external_storage = context.tryGetExternalTable(id->name))
+					external_tables[id->name] = external_storage;
+		}
+	}
+}
+
+
 void ExpressionAnalyzer::addExternalStorage(ASTFunction * node, size_t & name_id)
 {
 	IAST & args = *node->arguments;
@@ -542,8 +570,13 @@ void ExpressionAnalyzer::addExternalStorage(ASTFunction * node, size_t & name_id
 		{
 			ParserSelectQuery parser;
 
-			if (context.tryGetExternalTable(table->name))
+			StoragePtr existing_storage;
+
+			if (existing_storage = context.tryGetExternalTable(table->name))
+			{
+				external_tables[table->name] = existing_storage;
 				return;
+			}
 
 			String query = "SELECT * FROM " + table->name;
 			const char * begin = query.data();
@@ -573,7 +606,7 @@ void ExpressionAnalyzer::addExternalStorage(ASTFunction * node, size_t & name_id
 		ast_ident->kind = ASTIdentifier::Table;
 		ast_ident->name = external_storage->getTableName();
 		arg = ast_ident;
-		external_tables.push_back(external_storage);
+		external_tables[external_table_name] = external_storage;
 	}
 	else
 		throw Exception("GLOBAL [NOT] IN supports only SELECT data.", ErrorCodes::BAD_ARGUMENTS);
@@ -1177,6 +1210,8 @@ void ExpressionAnalyzer::processGlobalOperations()
 			++id;
 		addExternalStorage(dynamic_cast<ASTFunction *>(&*global_nodes[i]), id);
 	}
+
+	findExternalTables(ast);
 }
 
 bool ExpressionAnalyzer::appendArrayJoin(ExpressionActionsChain & chain, bool only_types)
diff --git a/dbms/src/Interpreters/InterpreterSelectQuery.cpp b/dbms/src/Interpreters/InterpreterSelectQuery.cpp
index d10d1a6f357..9e8a4bcc61f 100644
--- a/dbms/src/Interpreters/InterpreterSelectQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterSelectQuery.cpp
@@ -83,7 +83,8 @@ void InterpreterSelectQuery::init(BlockInputStreamPtr input_, const NamesAndType
 
 	/// Сохраняем в query context новые временные таблицы
 	for (auto & it : query_analyzer->external_tables)
-		context.addExternalTable(it->getTableName(), it);
+		if (!(context.tryGetExternalTable(it.first)))
+		context.addExternalTable(it.first, it.second);
 
 	if (input_)
 		streams.push_back(input_);
@@ -504,7 +505,7 @@ QueryProcessingStage::Enum InterpreterSelectQuery::executeFetchColumns(BlockInpu
 	if (!interpreter_subquery)
 	{
 		if (storage->isRemote())
-			storage->storeExternalTables(context.getExternalTables());
+			storage->storeExternalTables(query_analyzer->external_tables);
  		streams = storage->read(required_columns, query_ptr, settings_for_storage, from_stage, settings.max_block_size, settings.max_threads);
  		for (auto stream : streams)
  		{