MDEV-7827: Assertion `!table || (!table->read_set || bitmap_is_set(table->read_set, field_index))' failed in Field_long::val_str on EXPLAIN EXTENDED

(Solution by Sergei Petrunia)
It appeared that semijoin conditions was not iterated when we were updating used tables. So now they do.

1 files changed, 22 insertions, 0 deletions

diff --git a/mysql-test/t/derived.test b/mysql-test/t/derived.test
index ddce7f55292..e31ece80e90 100644
--- a/mysql-test/t/derived.test
+++ b/mysql-test/t/derived.test
@@ -506,3 +506,25 @@ select x.id, message from (select id from t1) x left join
 (select id, 1 as message from t2) y on x.id=y.id
 where coalesce(message,0) <> 0;
 drop table t1,t2;
+
+--echo #
+--echo # MDEV-7827: Assertion `!table || (!table->read_set ||
+--echo # bitmap_is_set(table->read_set, field_index))' failed
+--echo # in Field_long::val_str on EXPLAIN EXTENDED
+--echo #
+
+CREATE TABLE t1 (f1 INT, f2 INT, KEY(f2)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (6,9);
+
+CREATE TABLE t2 (f3 INT) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (2),(0);
+
+EXPLAIN EXTENDED
+SELECT f1 FROM ( SELECT * FROM t1 ) AS sq
+WHERE f1 IN (
+  SELECT f3 FROM t2 WHERE f2 IN (
+    SELECT f3 FROM t2 HAVING f3 >= 8
+  )
+);
+
+DROP TABLE t2,t1;