From 14c231c055bc37b4c6fc95e55f6c7c1ab69a34f8 Mon Sep 17 00:00:00 2001
From: Pavel Kartavyy <kartavyy@yandex-team.ru>
Date: Thu, 13 Nov 2014 15:27:42 +0300
Subject: [PATCH] dbms: filtered tables in 'show tables from' query
 [#METR-13667]

---
 .../include/DB/Storages/StorageSystemTables.h |  2 ++
 dbms/src/Storages/StorageSystemTables.cpp     | 32 +++++++++++++++++--
 .../0_stateless/00080_show_tables.reference   |  2 ++
 .../queries/0_stateless/00080_show_tables.sql |  9 ++++++
 4 files changed, 42 insertions(+), 3 deletions(-)
 create mode 100644 dbms/tests/queries/0_stateless/00080_show_tables.reference
 create mode 100644 dbms/tests/queries/0_stateless/00080_show_tables.sql

diff --git a/dbms/include/DB/Storages/StorageSystemTables.h b/dbms/include/DB/Storages/StorageSystemTables.h
index 67dca8aaf2b..d4b1dee4881 100644
--- a/dbms/include/DB/Storages/StorageSystemTables.h
+++ b/dbms/include/DB/Storages/StorageSystemTables.h
@@ -38,6 +38,8 @@ private:
 	NamesAndTypesList columns;
 
 	StorageSystemTables(const std::string & name_, const Context & context_);
+
+	ColumnWithNameAndType getFilteredDatabases(ASTPtr query);
 };
 
 }
diff --git a/dbms/src/Storages/StorageSystemTables.cpp b/dbms/src/Storages/StorageSystemTables.cpp
index 68acc504df7..2866d2453e5 100644
--- a/dbms/src/Storages/StorageSystemTables.cpp
+++ b/dbms/src/Storages/StorageSystemTables.cpp
@@ -2,6 +2,7 @@
 #include <DB/DataTypes/DataTypeString.h>
 #include <DB/DataStreams/OneBlockInputStream.h>
 #include <DB/Storages/StorageSystemTables.h>
+#include <DB/Common/VirtualColumnUtils.h>
 
 
 namespace DB
@@ -51,11 +52,19 @@ BlockInputStreams StorageSystemTables::read(
 
 	Poco::ScopedLock<Poco::Mutex> lock(context.getMutex());
 
-	for (Databases::const_iterator it = context.getDatabases().begin(); it != context.getDatabases().end(); ++it)
+	ColumnWithNameAndType filtered_databases_column = getFilteredDatabases(query);
+
+	for (size_t row_number = 0; row_number < filtered_databases_column.column->size(); ++row_number)
 	{
-		for (Tables::const_iterator jt = it->second.begin(); jt != it->second.end(); ++jt)
+		std::string database_name = filtered_databases_column.column->getDataAt(row_number).toString();
+		auto database_it = context.getDatabases().find(database_name);
+
+		if (database_it == context.getDatabases().end())
+			throw DB::Exception(std::string("Fail to find database " + database_name), DB::ErrorCodes::LOGICAL_ERROR);
+
+		for (Tables::const_iterator jt = database_it->second.begin(); jt != database_it->second.end(); ++jt)
 		{
-			col_db.column->insert(it->first);
+			col_db.column->insert(database_name);
 			col_name.column->insert(jt->first);
 			col_engine.column->insert(jt->second->getName());
 		}
@@ -64,5 +73,22 @@ BlockInputStreams StorageSystemTables::read(
 	return BlockInputStreams(1, new OneBlockInputStream(block));
 }
 
+ColumnWithNameAndType StorageSystemTables::getFilteredDatabases(ASTPtr query)
+{
+	ColumnWithNameAndType filtered_databases_column;
+	filtered_databases_column.name = "database";
+	filtered_databases_column.type = new DataTypeString;
+	filtered_databases_column.column = new ColumnString;
+
+	Block filtered_databases_block;
+	filtered_databases_block.insert(filtered_databases_column);
+	for (auto database_it = context.getDatabases().begin(); database_it != context.getDatabases().end(); ++database_it)
+	{
+		filtered_databases_column.column->insert(database_it->first);
+	}
+	VirtualColumnUtils::filterBlockWithQuery(query, filtered_databases_block, context);
+
+	return filtered_databases_column;
+}
 
 }
diff --git a/dbms/tests/queries/0_stateless/00080_show_tables.reference b/dbms/tests/queries/0_stateless/00080_show_tables.reference
new file mode 100644
index 00000000000..35d242ba79a
--- /dev/null
+++ b/dbms/tests/queries/0_stateless/00080_show_tables.reference
@@ -0,0 +1,2 @@
+A
+B
diff --git a/dbms/tests/queries/0_stateless/00080_show_tables.sql b/dbms/tests/queries/0_stateless/00080_show_tables.sql
new file mode 100644
index 00000000000..872b8e7e224
--- /dev/null
+++ b/dbms/tests/queries/0_stateless/00080_show_tables.sql
@@ -0,0 +1,9 @@
+DROP DATABASE IF EXISTS test_show_tables;
+
+CREATE DATABASE test_show_tables;
+
+CREATE TABLE test_show_tables.A (A UInt8) ENGINE = TinyLog;
+CREATE TABLE test_show_tables.B (A UInt8) ENGINE = TinyLog;
+
+SHOW TABLES from test_show_tables;
+