MDEV-19044 Alter table corrupts while applying the modification log

Problem:
========
- InnoDB reads the length of the variable length field wrongly
while applying the modification log of instant table.

Solution:
========
rec_init_offsets_comp_ordinary(): For the temporary instant
file record, InnoDB should read the length of the variable length
field from the record itself.

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

@@ -180,28 +180,5 @@ t3	CREATE TABLE `t3` (
   UNIQUE KEY `v2` (`v2`)
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 DROP TABLE t1,t2,t3;
-db.opt
-#
-#  MDEV-26198 Assertion `0' failed in row_log_table_apply_op during
-#		ADD PRIMARY KEY or OPTIMIZE TABLE
-#
-CREATE TABLE t1(f1 year default null, f2 year default null,
-f3 text, f4 year default null, f5 year default null,
-f6 year default null, f7 year default null,
-f8 year default null)ENGINE=InnoDB ROW_FORMAT=REDUNDANT;
-INSERT INTO t1 VALUES(1, 1, 1, 1, 1, 1, 1, 1);
-ALTER TABLE t1 ADD COLUMN f9 year default null, ALGORITHM=INPLACE;
-set DEBUG_SYNC="row_log_table_apply1_before SIGNAL con1_insert WAIT_FOR con1_finish";
-ALTER TABLE t1 ROW_FORMAT=REDUNDANT, ADD COLUMN f10 YEAR DEFAULT NULL, ALGORITHM=INPLACE;
-connect con1,localhost,root,,,;
-SET DEBUG_SYNC="now WAIT_FOR con1_insert";
-INSERT IGNORE INTO t1 (f3) VALUES ( 'b' );
-INSERT IGNORE INTO t1 (f3) VALUES ( 'l' );
-SET DEBUG_SYNC="now SIGNAL con1_finish";
-connection default;
-disconnect con1;
 SET DEBUG_SYNC=RESET;
-CHECK TABLE t1;
+db.opt
-Table	Op	Msg_type	Msg_text
-test.t1	check	status	OK
-DROP TABLE t1;

mysql-test/suite/innodb/r/instant_alter_debug,dynamic.rdiff

@@ -1,6 +1,9 @@
-@@ -470,4 +470,4 @@
+--- mysql-test/suite/innodb/r/instant_alter_debug.result	2024-02-27 12:22:59.612941388 +0530
++++ mysql-test/suite/innodb/r/instant_alter_debug,dynamic.reject	2024-02-27 12:23:09.924938462 +0530
+@@ -537,5 +537,5 @@
  FROM information_schema.global_status
  WHERE variable_name = 'innodb_instant_alter_column';
  instants
--33
+-35
-+32
++34
+ SET GLOBAL innodb_purge_rseg_truncate_frequency = @save_frequency;

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

@@ -479,14 +479,63 @@ SET DEBUG_SYNC="now WAIT_FOR try_insert";
 INSERT INTO t1 VALUES(1, 2);
 ERROR HY000: Lock wait timeout exceeded; try restarting transaction
 SET DEBUG_SYNC="now SIGNAL alter_progress";
-disconnect con1;
 connection default;
 DROP TABLE t1;
+#
+#  MDEV-26198 Assertion `0' failed in row_log_table_apply_op during
+#                ADD PRIMARY KEY or OPTIMIZE TABLE
+#
+CREATE TABLE t1(f1 year default null, f2 year default null,
+f3 text, f4 year default null, f5 year default null,
+f6 year default null, f7 year default null,
+f8 year default null)ENGINE=InnoDB;
+INSERT INTO t1 VALUES(1, 1, 1, 1, 1, 1, 1, 1);
+ALTER TABLE t1 ADD COLUMN f9 year default null, ALGORITHM=INPLACE;
+set DEBUG_SYNC="row_log_table_apply1_before SIGNAL con1_insert WAIT_FOR con1_finish";
+ALTER TABLE t1 ADD COLUMN f10 YEAR DEFAULT NULL, FORCE, ALGORITHM=INPLACE;
+connection con1;
+SET DEBUG_SYNC="now WAIT_FOR con1_insert";
+INSERT IGNORE INTO t1 (f3) VALUES ( 'b' );
+INSERT IGNORE INTO t1 (f3) VALUES ( 'l' );
+SET DEBUG_SYNC="now SIGNAL con1_finish";
+connection default;
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+DROP TABLE t1;
+#
+# MDEV-19044 Alter table corrupts while applying the
+#             modification log
+#
+CREATE TABLE t1 (
+f1 INT,
+f2 INT,
+f3 char(19) CHARACTER SET utf8mb3,
+f4 VARCHAR(500),
+f5 TEXT)ENGINE=InnoDB;
+INSERT INTO t1 VALUES(3, 1, REPEAT('a', 2), REPEAT("b", 20),'a');
+ALTER TABLE t1 ADD COLUMN f6 INT NOT NULL, ALGORITHM=INSTANT;
+INSERT INTO t1 VALUES(1, 2, REPEAT('InnoDB', 2),
+REPEAT("MariaDB", 20), REPEAT('a', 8000), 12);
+INSERT INTO t1 VALUES(1, 2, REPEAT('MYSQL', 2),
+REPEAT("MariaDB", 20), REPEAT('a', 8000), 12);
+SET DEBUG_SYNC='innodb_inplace_alter_table_enter SIGNAL con1_begin WAIT_FOR con1_update';
+ALTER TABLE t1 MODIFY COLUMN f2 INT NOT NULL, FORCE, ALGORITHM=INPLACE;
+connection con1;
+SET DEBUG_SYNC='now WAIT_FOR con1_begin';
+UPDATE t1 SET f2=204 order by f1 limit 2;
+SET DEBUG_SYNC='now SIGNAL con1_update';
+connection default;
+disconnect con1;
 SET DEBUG_SYNC=reset;
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+DROP TABLE t1;
 # End of 10.4 tests
-SET GLOBAL innodb_purge_rseg_truncate_frequency = @save_frequency;
 SELECT variable_value-@old_instant instants
 FROM information_schema.global_status
 WHERE variable_name = 'innodb_instant_alter_column';
 instants
-33
+35
+SET GLOBAL innodb_purge_rseg_truncate_frequency = @save_frequency;

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

@@ -202,32 +202,6 @@ SHOW CREATE TABLE t1;
 SHOW CREATE TABLE t2;
 SHOW CREATE TABLE t3;
 DROP TABLE t1,t2,t3;
-
+SET DEBUG_SYNC=RESET;
 --remove_files_wildcard $MYSQLD_DATADIR/test #sql*.frm
 --list_files $MYSQLD_DATADIR/test
-
---echo #
---echo #  MDEV-26198 Assertion `0' failed in row_log_table_apply_op during
---echo #		ADD PRIMARY KEY or OPTIMIZE TABLE
---echo #
-CREATE TABLE t1(f1 year default null, f2 year default null,
-                f3 text, f4 year default null, f5 year default null,
-		f6 year default null, f7 year default null,
-		f8 year default null)ENGINE=InnoDB ROW_FORMAT=REDUNDANT;
-INSERT INTO t1 VALUES(1, 1, 1, 1, 1, 1, 1, 1);
-ALTER TABLE t1 ADD COLUMN f9 year default null, ALGORITHM=INPLACE;
-set DEBUG_SYNC="row_log_table_apply1_before SIGNAL con1_insert WAIT_FOR con1_finish";
-send ALTER TABLE t1 ROW_FORMAT=REDUNDANT, ADD COLUMN f10 YEAR DEFAULT NULL, ALGORITHM=INPLACE;
-
-connect(con1,localhost,root,,,);
-SET DEBUG_SYNC="now WAIT_FOR con1_insert";
-INSERT IGNORE INTO t1 (f3) VALUES ( 'b' );
-INSERT IGNORE INTO t1 (f3) VALUES ( 'l' );
-SET DEBUG_SYNC="now SIGNAL con1_finish";
-
-connection default;
-reap;
-disconnect con1;
-SET DEBUG_SYNC=RESET;
-CHECK TABLE t1;
-DROP TABLE t1;

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

@@ -549,16 +549,67 @@ SET DEBUG_SYNC="now WAIT_FOR try_insert";
 --error ER_LOCK_WAIT_TIMEOUT
 INSERT INTO t1 VALUES(1, 2);
 SET DEBUG_SYNC="now SIGNAL alter_progress";
-disconnect con1;
 connection default;
 reap;
 DROP TABLE t1;
+
+--echo #
+--echo #  MDEV-26198 Assertion `0' failed in row_log_table_apply_op during
+--echo #                ADD PRIMARY KEY or OPTIMIZE TABLE
+--echo #
+CREATE TABLE t1(f1 year default null, f2 year default null,
+                f3 text, f4 year default null, f5 year default null,
+                f6 year default null, f7 year default null,
+                f8 year default null)ENGINE=InnoDB;
+INSERT INTO t1 VALUES(1, 1, 1, 1, 1, 1, 1, 1);
+ALTER TABLE t1 ADD COLUMN f9 year default null, ALGORITHM=INPLACE;
+set DEBUG_SYNC="row_log_table_apply1_before SIGNAL con1_insert WAIT_FOR con1_finish";
+send ALTER TABLE t1 ADD COLUMN f10 YEAR DEFAULT NULL, FORCE, ALGORITHM=INPLACE;
+
+connection con1;
+SET DEBUG_SYNC="now WAIT_FOR con1_insert";
+INSERT IGNORE INTO t1 (f3) VALUES ( 'b' );
+INSERT IGNORE INTO t1 (f3) VALUES ( 'l' );
+SET DEBUG_SYNC="now SIGNAL con1_finish";
+
+connection default;
+reap;
+CHECK TABLE t1;
+DROP TABLE t1;
+
+--echo #
+--echo # MDEV-19044 Alter table corrupts while applying the
+--echo #             modification log
+--echo #
+CREATE TABLE t1 (
+        f1 INT,
+        f2 INT,
+        f3 char(19) CHARACTER SET utf8mb3,
+        f4 VARCHAR(500),
+        f5 TEXT)ENGINE=InnoDB;
+INSERT INTO t1 VALUES(3, 1, REPEAT('a', 2), REPEAT("b", 20),'a');
+ALTER TABLE t1 ADD COLUMN f6 INT NOT NULL, ALGORITHM=INSTANT;
+INSERT INTO t1 VALUES(1, 2, REPEAT('InnoDB', 2),
+                      REPEAT("MariaDB", 20), REPEAT('a', 8000), 12);
+INSERT INTO t1 VALUES(1, 2, REPEAT('MYSQL', 2),
+                      REPEAT("MariaDB", 20), REPEAT('a', 8000), 12);
+SET DEBUG_SYNC='innodb_inplace_alter_table_enter SIGNAL con1_begin WAIT_FOR con1_update';
+send ALTER TABLE t1 MODIFY COLUMN f2 INT NOT NULL, FORCE, ALGORITHM=INPLACE;
+connection con1;
+SET DEBUG_SYNC='now WAIT_FOR con1_begin';
+UPDATE t1 SET f2=204 order by f1 limit 2;
+SET DEBUG_SYNC='now SIGNAL con1_update';
+connection default;
+reap;
+disconnect con1;
 SET DEBUG_SYNC=reset;
+CHECK TABLE t1;
+DROP TABLE t1;
 
 --echo # End of 10.4 tests
 
-SET GLOBAL innodb_purge_rseg_truncate_frequency = @save_frequency;
-
 SELECT variable_value-@old_instant instants
 FROM information_schema.global_status
 WHERE variable_name = 'innodb_instant_alter_column';
+
+SET GLOBAL innodb_purge_rseg_truncate_frequency = @save_frequency;

storage/innobase/rem/rem0rec.cc

@@ -421,7 +421,7 @@ start:
 		}
 
 		if (!field->fixed_len
-		    || (format == REC_LEAF_TEMP
+		    || (format <= REC_LEAF_TEMP_INSTANT
 			&& !dict_col_get_fixed_size(col, true))) {
 			/* Variable-length field: read the length */
 			len = *lens--;