MDEV-29186 Query cache makes virtual column function RAND() non-random

Author: vuvova

mysql-test/suite/vcol/r/query_cache.result

@@ -0,0 +1,20 @@
+#
+# MDEV-29186 Query cache makes virtual column function RAND() non-random
+#
+set global query_cache_type=1;
+set query_cache_type=1;
+set rand_seed1=1234567890, rand_seed2=20;
+create table t1 (a int, b float as (rand()));
+insert into t1 (a) values (1);
+select * from t1;
+a	b
+1	0.449343
+select * from t1;
+a	b
+1	0.797372
+set global query_cache_type=default;
+select * from t1;
+a	b
+1	0.638829
+drop table t1;
+# End of 10.11 tests

mysql-test/suite/vcol/t/query_cache.test

@@ -0,0 +1,18 @@
+--echo #
+--echo # MDEV-29186 Query cache makes virtual column function RAND() non-random
+--echo #
+
+set global query_cache_type=1;
+set query_cache_type=1;
+set rand_seed1=1234567890, rand_seed2=20;
+create table t1 (a int, b float as (rand()));
+insert into t1 (a) values (1);
+--disable_ps2_protocol
+select * from t1;
+select * from t1;
+set global query_cache_type=default;
+select * from t1;
+--enable_ps2_protocol
+drop table t1;
+
+--echo # End of 10.11 tests

sql/item_func.cc

@@ -2857,6 +2857,7 @@ bool Item_func_rand::fix_fields(THD *thd,Item **ref)
   if (Item_real_func::fix_fields(thd, ref))
     return TRUE;
   used_tables_cache|= RAND_TABLE_BIT;
+  thd->lex->safe_to_cache_query= 0;
   if (arg_count)
   {					// Only use argument once in query
     /*