MDEV-31279 Crash when lateral derived is guaranteed to return no rows

Consider this query SELECT t1.* FROM t1, (SELECT t2.b FROM t2 WHERE NOT EXISTS (SELECT 1 FROM t3) GROUP BY b) sq where sq.b = t1.a; If SELECT 1 FROM t3 is expensive, for example t3 has > thd->variables.expensive_subquery_limit, first evaluation is deferred to mysql_derived_fill(). There it is noted that, in the above case NOT EXISTS (SELECT 1 FROM t3) is constant and false. This causes the join variable zero_result_cause to be set to "Impossible WHERE noticed after reading const tables" and the handler for this join is never "opened" via handler::ha_open. When mysql_derived_fill() is called for the next group of results, this unopened handler is not taken into account. reviewed by Igor Babaev (igor@mariadb.com)

Author: mariadb-RexJohnston

mysql-test/main/derived_split_innodb.result

@@ -826,4 +826,19 @@ SELECT * FROM t1 JOIN t2 WHERE (t1.a, t2.b) IN (SELECT * FROM v);
 a	b
 DROP VIEW v;
 DROP TABLE t1, t2, t3;
+#
+# MDEV-31279 Crash when lateral derived is guaranteed to return no rows
+#
+CREATE TABLE t1 (a CHAR(1)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES ('1'),('2');
+CREATE TABLE t2 (b INT, KEY(b)) ENGINE=MyISAM;
+ALTER TABLE t2 DISABLE KEYS;
+INSERT INTO t2 VALUES (1),(2),(3);
+ALTER TABLE t2 ENABLE KEYS;
+CREATE TABLE t3 (c INT) ENGINE=MyISAM;
+INSERT INTO t3 (c) SELECT seq FROM seq_1_to_101;
+SELECT * FROM t1 WHERE t1.a IN (SELECT b FROM
+(SELECT t2.b FROM t2 WHERE NOT EXISTS (SELECT 1 FROM t3) GROUP BY b) sq);
+a
+DROP TABLE t1, t2, t3;
 # End of 10.4 tests

mysql-test/main/derived_split_innodb.test

@@ -483,4 +483,22 @@ SELECT * FROM t1 JOIN t2 WHERE (t1.a, t2.b) IN (SELECT * FROM v);
 DROP VIEW v;
 DROP TABLE t1, t2, t3;
 
+--echo #
+--echo # MDEV-31279 Crash when lateral derived is guaranteed to return no rows
+--echo #
+
+CREATE TABLE t1 (a CHAR(1)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES ('1'),('2');
+CREATE TABLE t2 (b INT, KEY(b)) ENGINE=MyISAM;
+ALTER TABLE t2 DISABLE KEYS;
+INSERT INTO t2 VALUES (1),(2),(3);
+ALTER TABLE t2 ENABLE KEYS;
+CREATE TABLE t3 (c INT) ENGINE=MyISAM;
+INSERT INTO t3 (c) SELECT seq FROM seq_1_to_101;
+
+SELECT * FROM t1 WHERE t1.a IN (SELECT b FROM
+ (SELECT t2.b FROM t2 WHERE NOT EXISTS (SELECT 1 FROM t3) GROUP BY b) sq);
+
+DROP TABLE t1, t2, t3;
+
 --echo # End of 10.4 tests

sql/sql_derived.cc

@@ -1227,6 +1227,9 @@ bool mysql_derived_fill(THD *thd, LEX *lex, TABLE_LIST *derived)
  goto err;
  JOIN *join= unit->first_select()->join;
  join->first_record= false;
+ if (join->zero_result_cause)
+ goto err;
+
  for (uint i= join->top_join_tab_count;
  i < join->top_join_tab_count + join->aggr_tables;
  i++)