Fixed bug mdev-11674.

1. The rows of a recursive CTE at some point may overflow
the HEAP temporary table containing them. At this point
the table is converted to a MyISAM temporary table and the
new added rows are placed into this MyISAM table.
A bug in the of select_union_recursive::send_data prevented
the server from writing the row that caused the overflow
into the temporary table used for the result of the iteration
steps. This could lead, in particular,to a premature end
of the iterations.
2. The method TABLE::insert_all_rows_into() that was used
to copy all rows of one temporary table into another
did not take into account that the destination temporary
table must be converted to a MyISAM table at some point.
This patch fixed this problem. It also renamed the method
into TABLE::insert_all_rows_into_tmp_table() and added
an extra parameter needed for the conversion.

1 files changed, 16 insertions, 0 deletions

diff --git a/mysql-test/r/cte_recursive.result b/mysql-test/r/cte_recursive.result
index 0cc88d27e23..d5476aec1c4 100644
--- a/mysql-test/r/cte_recursive.result
+++ b/mysql-test/r/cte_recursive.result
@@ -2327,3 +2327,19 @@ a	b	dist
 7	6	3
 DROP VIEW edges2;
 DROP TABLE edges;
+#
+# MDEV-11674: recursive CTE table that cannot be stored
+#             in a heap table
+#
+create table t1 (id int, test_data varchar(36));
+insert into t1(id, test_data)
+select id, test_data
+from (
+with recursive data_generator(id, test_data) as (
+select 1 as id, uuid() as test_data
+union all
+select id + 1, uuid() from data_generator where id < 150000
+)
+select * from data_generator
+) as a;
+drop table t1;