From 435394242ca5b08d179be16a6bfe966a8d243764 Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@yandex-team.ru>
Date: Sun, 17 Aug 2014 06:17:23 +0400
Subject: [PATCH] dbms: improved performance of filtering [#METR-2944].

---
 dbms/src/DataStreams/FilterBlockInputStream.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/dbms/src/DataStreams/FilterBlockInputStream.cpp b/dbms/src/DataStreams/FilterBlockInputStream.cpp
index 3a36d42b710..75de7654b96 100644
--- a/dbms/src/DataStreams/FilterBlockInputStream.cpp
+++ b/dbms/src/DataStreams/FilterBlockInputStream.cpp
@@ -88,6 +88,15 @@ Block FilterBlockInputStream::readImpl()
 		if (filtered_rows == 0)
 			continue;
 
+		/// Если через фильтр проходят все строчки.
+		if (filtered_rows == filter.size())
+		{
+			/// Заменим столбец с фильтром на константу.
+			res.getByPosition(filter_column).column = new ColumnConstUInt8(filtered_rows, 1);
+			/// Остальные столбцы трогать не нужно.
+			return res;
+		}
+
 		/// Фильтруем остальные столбцы.
 		for (size_t i = 0; i < columns; ++i)
 		{