Added a test just in case #880

dbms/tests/queries/0_stateless/00740_optimize_predicate_expression.sql

@@ -0,0 +1,35 @@
+DROP TABLE IF EXISTS users.perf;
+CREATE TABLE users.perf (site String, user_id UInt64, z Float64) ENGINE = Log;
+
+SELECT * FROM (SELECT perf_1.z AS z_1 FROM users.perf AS perf_1);
+
+SELECT sum(mul)/sqrt(sum(sqr_dif_1) * sum(sqr_dif_2)) AS z_r
+FROM(
+SELECT 
+        (SELECT avg(z_1) AS z_1_avg, 
+                avg(z_2) AS z_2_avg
+        FROM ( 
+            SELECT perf_1.site, perf_1.z AS z_1
+            FROM users.perf AS perf_1
+            WHERE user_id = 000
+        ) ALL INNER JOIN (
+            SELECT perf_2.site, perf_2.z AS z_2
+            FROM users.perf AS perf_2
+            WHERE user_id = 999
+        ) USING site) as avg_values,
+       z_1 - avg_values.1 AS dif_1, 
+       z_2 - avg_values.2 AS dif_2, 
+       dif_1 * dif_2 AS mul, 
+       dif_1*dif_1 AS sqr_dif_1, 
+       dif_2*dif_2 AS sqr_dif_2
+FROM (
+            SELECT perf_1.site, perf_1.z AS z_1
+            FROM users.perf AS perf_1
+            WHERE user_id = 000
+) ALL INNER JOIN (
+            SELECT perf_2.site, perf_2.z AS z_2
+            FROM users.perf AS perf_2
+            WHERE user_id = 999
+) USING site);
+
+DROP TABLE users.perf;

dbms/tests/queries/0_stateless/00741_client_comment_multiline.sql

@@ -0,0 +1 @@
+CREATE DATABASE IF NOT EXISTS test; -- foo