MDEV-10766: Queries which start with WITH clause do not get inserted into query cache

Added conditions so that the WITH queries are also added to the query cache

mysql-test/r/query_cache.result

@@ -2136,6 +2136,38 @@ Qcache_hits	1
 use test;
 drop database `foo.bar`;
 End of 10.0 tests
+#
+# MDEV-10766 Queries which start with WITH clause do not get
+# inserted into query cache
+#
+flush status;
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	0
+create table t1 (i int);
+with cte as (select * from t1) select * from cte;
+i
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	0
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	0
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	0
+with cte as (select * from t1) select * from cte;
+i
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	0
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	0
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	0
+drop table t1;
 restore defaults
 SET GLOBAL query_cache_type= default;
 SET GLOBAL query_cache_size= default;

mysql-test/t/query_cache.test

@@ -1750,6 +1750,23 @@ drop database `foo.bar`;
 
 --echo End of 10.0 tests
 
+--echo #
+--echo # MDEV-10766 Queries which start with WITH clause do not get
+--echo # inserted into query cache
+--echo #
+flush status;
+show status like "Qcache_inserts";
+create table t1 (i int);
+with cte as (select * from t1) select * from cte;
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+with cte as (select * from t1) select * from cte;
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+drop table t1;
+
 --echo restore defaults
 SET GLOBAL query_cache_type= default;
 SET GLOBAL query_cache_size= default;

sql/sql_cache.cc

@@ -1828,7 +1828,10 @@ Query_cache::send_result_to_client(THD *thd, char *org_sql, uint query_length)
   }
   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'))
+       my_toupper(system_charset_info, sql[2]) != 'L') &&
+      (my_toupper(system_charset_info, sql[0]) != 'W' ||
+       my_toupper(system_charset_info, sql[1]) != 'I' ||
+       my_toupper(system_charset_info, sql[2]) != 'T'))
   {
     DBUG_PRINT("qcache", ("The statement is not a SELECT; Not cached"));
     goto err;