MDEV-14660 Assertion failure in lock_move_rec_list_start() after instant ADD COLUMN

lock_move_rec_list_start(): Relax a too strict assertion.
This function can be invoked on the leftmost leaf page, after all.
So, the first record of each page can be a 'default row' record,
but the 'default row' record must never be locked.

mysql-test/suite/innodb/r/instant_alter.result

@@ -353,6 +353,22 @@ id	c2	c4	c5	c6	c8	phrase	b
 3	3	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	The quick brown fox jumps over the lazy dog	
 4	0	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	The quick brown fox jumps over the lazy dog	😱
 5	9	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	ääH	binary line of business
+CREATE TABLE t4
+(id INT, foo INT DEFAULT 0, c1 VARCHAR(4000),
+p GEOMETRY NOT NULL DEFAULT ST_GeomFromText('LINESTRING(0 0,0 1,1 1)'),
+PRIMARY KEY(id,foo))
+ENGINE=InnoDB ROW_FORMAT=REDUNDANT;
+INSERT INTO t4 (id,c1) VALUES (1, REPEAT('a', 4000)), (2, REPEAT('a', 4000));
+ALTER TABLE t4 ADD COLUMN d1 INT;
+BEGIN;
+UPDATE t4 SET c1 = repeat('1', 4000), foo=1 WHERE id=1;
+INSERT INTO t4 (id,c1) VALUES (1, REPEAT('a', 4000));
+UPDATE t4 SET c1 = repeat('2', 4000), foo=1 WHERE id=2;
+ROLLBACK;
+BEGIN;
+UPDATE t4 SET d1 = 1,foo=2 WHERE id=1;
+INSERT INTO t4 (id,foo,c1) VALUES (1, 1, REPEAT('1', 4000));
+COMMIT;
 CREATE TABLE big
 (id INT PRIMARY KEY, c1 VARCHAR(4000), c2 VARCHAR(4000), c3 VARCHAR(1000),
 p POINT NOT NULL DEFAULT ST_GeomFromText('POINT(0 0)'), SPATIAL INDEX(p))
@@ -413,7 +429,7 @@ clust_index_size
 3
 connection default;
 InnoDB		0 transactions not purged
-DROP TABLE t1,t2,t3,big;
+DROP TABLE t1,t2,t3,t4,big;
 CREATE TABLE t1
 (id INT PRIMARY KEY, c2 INT UNIQUE,
 c3 POINT NOT NULL DEFAULT ST_GeomFromText('POINT(3 4)'),
@@ -713,6 +729,22 @@ id	c2	c4	c5	c6	c8	phrase	b
 3	3	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	The quick brown fox jumps over the lazy dog	
 4	0	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	The quick brown fox jumps over the lazy dog	😱
 5	9	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	ääH	binary line of business
+CREATE TABLE t4
+(id INT, foo INT DEFAULT 0, c1 VARCHAR(4000),
+p GEOMETRY NOT NULL DEFAULT ST_GeomFromText('LINESTRING(0 0,0 1,1 1)'),
+PRIMARY KEY(id,foo))
+ENGINE=InnoDB ROW_FORMAT=COMPACT;
+INSERT INTO t4 (id,c1) VALUES (1, REPEAT('a', 4000)), (2, REPEAT('a', 4000));
+ALTER TABLE t4 ADD COLUMN d1 INT;
+BEGIN;
+UPDATE t4 SET c1 = repeat('1', 4000), foo=1 WHERE id=1;
+INSERT INTO t4 (id,c1) VALUES (1, REPEAT('a', 4000));
+UPDATE t4 SET c1 = repeat('2', 4000), foo=1 WHERE id=2;
+ROLLBACK;
+BEGIN;
+UPDATE t4 SET d1 = 1,foo=2 WHERE id=1;
+INSERT INTO t4 (id,foo,c1) VALUES (1, 1, REPEAT('1', 4000));
+COMMIT;
 CREATE TABLE big
 (id INT PRIMARY KEY, c1 VARCHAR(4000), c2 VARCHAR(4000), c3 VARCHAR(1000),
 p POINT NOT NULL DEFAULT ST_GeomFromText('POINT(0 0)'), SPATIAL INDEX(p))
@@ -773,7 +805,7 @@ clust_index_size
 3
 connection default;
 InnoDB		0 transactions not purged
-DROP TABLE t1,t2,t3,big;
+DROP TABLE t1,t2,t3,t4,big;
 CREATE TABLE t1
 (id INT PRIMARY KEY, c2 INT UNIQUE,
 c3 POINT NOT NULL DEFAULT ST_GeomFromText('POINT(3 4)'),
@@ -1073,6 +1105,22 @@ id	c2	c4	c5	c6	c8	phrase	b
 3	3	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	The quick brown fox jumps over the lazy dog	
 4	0	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	The quick brown fox jumps over the lazy dog	😱
 5	9	1970-01-01 03:00:42	1970-01-01 03:00:42	NULL	1970-01-01	ääH	binary line of business
+CREATE TABLE t4
+(id INT, foo INT DEFAULT 0, c1 VARCHAR(4000),
+p GEOMETRY NOT NULL DEFAULT ST_GeomFromText('LINESTRING(0 0,0 1,1 1)'),
+PRIMARY KEY(id,foo))
+ENGINE=InnoDB ROW_FORMAT=DYNAMIC;
+INSERT INTO t4 (id,c1) VALUES (1, REPEAT('a', 4000)), (2, REPEAT('a', 4000));
+ALTER TABLE t4 ADD COLUMN d1 INT;
+BEGIN;
+UPDATE t4 SET c1 = repeat('1', 4000), foo=1 WHERE id=1;
+INSERT INTO t4 (id,c1) VALUES (1, REPEAT('a', 4000));
+UPDATE t4 SET c1 = repeat('2', 4000), foo=1 WHERE id=2;
+ROLLBACK;
+BEGIN;
+UPDATE t4 SET d1 = 1,foo=2 WHERE id=1;
+INSERT INTO t4 (id,foo,c1) VALUES (1, 1, REPEAT('1', 4000));
+COMMIT;
 CREATE TABLE big
 (id INT PRIMARY KEY, c1 VARCHAR(4000), c2 VARCHAR(4000), c3 VARCHAR(1000),
 p POINT NOT NULL DEFAULT ST_GeomFromText('POINT(0 0)'), SPATIAL INDEX(p))
@@ -1133,11 +1181,11 @@ clust_index_size
 3
 connection default;
 InnoDB		0 transactions not purged
-DROP TABLE t1,t2,t3,big;
+DROP TABLE t1,t2,t3,t4,big;
 disconnect analyze;
 SELECT variable_value-@old_instant instants
 FROM information_schema.global_status
 WHERE variable_name = 'innodb_instant_alter_column';
 instants
-30
+33
 SET GLOBAL innodb_purge_rseg_truncate_frequency= @saved_frequency;

mysql-test/suite/innodb/t/instant_alter.test

@@ -236,6 +236,26 @@ ALTER TABLE t3 DROP c3, DROP c7;
 --disable_info
 SELECT * FROM t3;
 
+eval CREATE TABLE t4
+(id INT, foo INT DEFAULT 0, c1 VARCHAR(4000),
+ p GEOMETRY NOT NULL DEFAULT ST_GeomFromText('LINESTRING(0 0,0 1,1 1)'),
+ PRIMARY KEY(id,foo))
+$engine;
+
+INSERT INTO t4 (id,c1) VALUES (1, REPEAT('a', 4000)), (2, REPEAT('a', 4000));
+ALTER TABLE t4 ADD COLUMN d1 INT;
+
+BEGIN;
+UPDATE t4 SET c1 = repeat('1', 4000), foo=1 WHERE id=1;
+INSERT INTO t4 (id,c1) VALUES (1, REPEAT('a', 4000));
+UPDATE t4 SET c1 = repeat('2', 4000), foo=1 WHERE id=2;
+ROLLBACK;
+
+BEGIN;
+UPDATE t4 SET d1 = 1,foo=2 WHERE id=1;
+INSERT INTO t4 (id,foo,c1) VALUES (1, 1, REPEAT('1', 4000));
+COMMIT;
+
 eval CREATE TABLE big
 (id INT PRIMARY KEY, c1 VARCHAR(4000), c2 VARCHAR(4000), c3 VARCHAR(1000),
  p POINT NOT NULL DEFAULT ST_GeomFromText('POINT(0 0)'), SPATIAL INDEX(p))
@@ -279,7 +299,7 @@ WHERE name = 'test/big';
 connection default;
 
 --source include/wait_all_purged.inc
-DROP TABLE t1,t2,t3,big;
+DROP TABLE t1,t2,t3,t4,big;
 
 dec $format;
 }

storage/innobase/lock/lock0lock.cc

@@ -3833,8 +3833,9 @@ lock_move_rec_list_start(
 		reset the lock bits on the old */
 
 		while (rec1 != rec) {
-			ut_ad(!page_rec_is_default_row(rec1));
-			ut_ad(!page_rec_is_default_row(rec2));
+			ut_ad(page_rec_is_default_row(rec1)
+			      == page_rec_is_default_row(rec2));
+			ut_d(const rec_t* const prev = rec1);
 
 			ulint	rec1_heap_no;
 			ulint	rec2_heap_no;
@@ -3858,6 +3859,8 @@ lock_move_rec_list_start(
 
 			if (rec1_heap_no < lock->un_member.rec_lock.n_bits
 			    && lock_rec_reset_nth_bit(lock, rec1_heap_no)) {
+				ut_ad(!page_rec_is_default_row(prev));
+
 				if (type_mode & LOCK_WAIT) {
 					lock_reset_lock_and_trx_wait(lock);
 				}