We should skip beggining '(' characters when test query on possibility

to be in the query cache. (BUG#14652)


mysql-test/r/query_cache.result:
  BUG#14652 test suite.
mysql-test/t/query_cache.test:
  BUG#14652 test suite.
sql/sql_cache.cc:
  We should skip beggining '(' characters when test query on possibility
  to be in the query cache.

mysql-test/r/query_cache.result

@@ -982,4 +982,29 @@ show status like "Qcache_hits";
 Variable_name	Value
 Qcache_hits	1
 drop table t1;
+create table t1 (a int);
+flush status;
+(select a from t1) union (select a from t1);
+a
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	0
+(select a from t1) union (select a from t1);
+a
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	1
+drop table t1;
 set GLOBAL query_cache_size=0;

mysql-test/t/query_cache.test

@@ -712,6 +712,21 @@ show status like "Qcache_inserts";
 show status like "Qcache_hits";
 drop table t1;
 
+#
+# BUG#14652: Queries with leading '(' characters.
+#
+create table t1 (a int);
+flush status;
+(select a from t1) union (select a from t1);
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+(select a from t1) union (select a from t1);
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+drop table t1;
+
 set GLOBAL query_cache_size=0;
 
 # End of 4.1 tests

sql/sql_cache.cc

@@ -956,16 +956,26 @@ Query_cache::send_result_to_client(THD *thd, char *sql, uint query_length)
     goto err;
   }
 
-  /*
-    Test if the query is a SELECT
-    (pre-space is removed in dispatch_command)
-  */
-  if (my_toupper(system_charset_info, sql[0]) != 'S' || 
-      my_toupper(system_charset_info, sql[1]) != 'E' ||
-      my_toupper(system_charset_info,sql[2]) !='L')
   {
-    DBUG_PRINT("qcache", ("The statement is not a SELECT; Not cached"));
-    goto err;
+    uint i= 0;
+    /*
+      Skip '(' characters in queries like following:
+      (select a from t1) union (select a from t1);
+    */
+    while (sql[i]=='(')
+      i++;
+
+    /*
+      Test if the query is a SELECT
+      (pre-space is removed in dispatch_command)
+    */
+    if (my_toupper(system_charset_info, sql[i])     != 'S' ||
+        my_toupper(system_charset_info, sql[i + 1]) != 'E' ||
+        my_toupper(system_charset_info, sql[i + 2]) != 'L')
+    {
+      DBUG_PRINT("qcache", ("The statement is not a SELECT; Not cached"));
+      goto err;
+    }
   }
 
   STRUCT_LOCK(&structure_guard_mutex);