MDEV-38988 : Assertion failure in Protocol::end_statement or lack of warning upon query with INTERSECT and LIMIT ROWS EXAMINED

mysql-test/main/except.result

@@ -710,3 +710,59 @@ SELECT * FROM t WHERE i != ANY ( SELECT 3 EXCEPT SELECT 3 );
 i
 drop table t;
 # End of 10.3 tests
+#
+# MDEV-38988: Assertion failure in Protocol::end_statement or
+# lack of warning upon query with INTERSECT and LIMIT ROWS EXAMINED
+#
+CREATE TABLE t (a INT PRIMARY KEY, b INT) ENGINE=InnoDB;
+INSERT INTO t SELECT seq, seq FROM seq_1_to_30;
+(SELECT a FROM t LIMIT ROWS EXAMINED 100) EXCEPT ALL (SELECT a FROM t);
+a
+21
+22
+23
+24
+25
+26
+27
+28
+29
+30
+Warnings:
+Warning	1931	Query execution was interrupted. The query exceeded LIMIT ROWS EXAMINED 100. The query result may be incomplete
+DROP TABLE t;
+CREATE TABLE t (a INT PRIMARY KEY, b INT) ENGINE=MyISAM;
+INSERT INTO t SELECT seq, seq FROM seq_1_to_30;
+(SELECT a FROM t LIMIT ROWS EXAMINED 100) EXCEPT ALL (SELECT a FROM t);
+a
+21
+22
+23
+24
+25
+26
+27
+28
+29
+30
+Warnings:
+Warning	1931	Query execution was interrupted. The query exceeded LIMIT ROWS EXAMINED 100. The query result may be incomplete
+DROP TABLE t;
+CREATE TABLE t (id INT PRIMARY KEY, f VARCHAR(16)) ENGINE=InnoDB;
+INSERT INTO t SELECT seq, '' FROM seq_1_to_8650;
+(SELECT f FROM t WHERE id BETWEEN 7000 AND 9000 LIMIT ROWS EXAMINED 8000)
+INTERSECT
+(SELECT f FROM t WHERE id BETWEEN 7000 AND 9000 LIMIT ROWS EXAMINED 8000);
+f
+
+DROP TABLE t;
+CREATE TABLE t (id INT PRIMARY KEY, f VARCHAR(16)) ENGINE=MyISAM;
+INSERT INTO t SELECT seq, '' FROM seq_1_to_8650;
+(SELECT f FROM t WHERE id BETWEEN 7000 AND 9000 LIMIT ROWS EXAMINED 8000)
+INTERSECT
+(SELECT f FROM t WHERE id BETWEEN 7000 AND 9000 LIMIT ROWS EXAMINED 8000);
+f
+
+Warnings:
+Warning	1931	Query execution was interrupted. The query exceeded LIMIT ROWS EXAMINED 8000. The query result may be incomplete
+DROP TABLE t;

mysql-test/main/except.test

@@ -99,3 +99,39 @@ drop table t;
 
 
 --echo # End of 10.3 tests
+
+--echo #
+--echo # MDEV-38988: Assertion failure in Protocol::end_statement or
+--echo # lack of warning upon query with INTERSECT and LIMIT ROWS EXAMINED
+--echo #
+
+--source include/have_innodb.inc
+--source include/have_sequence.inc
+
+CREATE TABLE t (a INT PRIMARY KEY, b INT) ENGINE=InnoDB;
+INSERT INTO t SELECT seq, seq FROM seq_1_to_30;
+(SELECT a FROM t LIMIT ROWS EXAMINED 100) EXCEPT ALL (SELECT a FROM t);
+
+DROP TABLE t;
+
+CREATE TABLE t (a INT PRIMARY KEY, b INT) ENGINE=MyISAM;
+INSERT INTO t SELECT seq, seq FROM seq_1_to_30;
+(SELECT a FROM t LIMIT ROWS EXAMINED 100) EXCEPT ALL (SELECT a FROM t);
+
+DROP TABLE t;
+
+CREATE TABLE t (id INT PRIMARY KEY, f VARCHAR(16)) ENGINE=InnoDB;
+INSERT INTO t SELECT seq, '' FROM seq_1_to_8650;
+(SELECT f FROM t WHERE id BETWEEN 7000 AND 9000 LIMIT ROWS EXAMINED 8000)
+INTERSECT
+(SELECT f FROM t WHERE id BETWEEN 7000 AND 9000 LIMIT ROWS EXAMINED 8000);
+
+DROP TABLE t;
+
+CREATE TABLE t (id INT PRIMARY KEY, f VARCHAR(16)) ENGINE=MyISAM;
+INSERT INTO t SELECT seq, '' FROM seq_1_to_8650;
+(SELECT f FROM t WHERE id BETWEEN 7000 AND 9000 LIMIT ROWS EXAMINED 8000)
+INTERSECT
+(SELECT f FROM t WHERE id BETWEEN 7000 AND 9000 LIMIT ROWS EXAMINED 8000);
+
+DROP TABLE t;

sql/sql_union.cc

@@ -2434,7 +2434,7 @@ bool st_select_lex_unit::exec_inner()
 	  }
 	}
       }
-      if (unlikely(saved_error))
+      if (thd->killed != ABORT_QUERY && unlikely(saved_error))
       {
         error= saved_error;
         goto err;