Bug#36840107: mysql crash after update inplace in instant ddl redundant table

Updating newly added column's value for the older version row
must not be "in place update", because the older row might not have
even flags space for the new columns.

This bug leads the updating newly added column's value for
the older version row to be "in place update" wrongly.
The reason is rec_get_instant_offset() doesn't treat NULL default value
of the newly added columns as DEFAULT value.

This fix adds REC_OFFS_DEFAULT bit for NULL default value
at rec_get_instant_offset().

Change-Id: I109f4e2ff6836767eec710cca3851dcbe8dde972

Author: Yasufumi Kinoshita

mysql-test/suite/innodb/include/instant_add_column_debug.inc

@@ -48,3 +48,13 @@ SHOW CREATE TABLE t1;
 SELECT * FROM t1;
 
 DROP TABLE t1;
+
+#
+# Bug#36840107 mysql crash after update inplace in instant ddl redundant table
+#
+--eval CREATE TABLE t1 (a INT, b INT) row_format=$row_format
+INSERT INTO t1 VALUES(0,0);
+ALTER TABLE t1 ADD COLUMN c varchar(25)  DEFAULT NULL, ALGORITHM=INSTANT;
+UPDATE t1 SET c="" WHERE a=0;
+SELECT * FROM t1;
+DROP TABLE t1;

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

@@ -39,6 +39,14 @@ a	b	d
 8	6	20
 10	1	10
 DROP TABLE t1;
+CREATE TABLE t1 (a INT, b INT) row_format=REDUNDANT;
+INSERT INTO t1 VALUES(0,0);
+ALTER TABLE t1 ADD COLUMN c varchar(25)  DEFAULT NULL, ALGORITHM=INSTANT;
+UPDATE t1 SET c="" WHERE a=0;
+SELECT * FROM t1;
+a	b	c
+0	0	
+DROP TABLE t1;
 ############################################
 # Test instant ADD COLUMN for DYNAMIC format
 ############################################
@@ -80,6 +88,14 @@ a	b	d
 8	6	20
 10	1	10
 DROP TABLE t1;
+CREATE TABLE t1 (a INT, b INT) row_format=DYNAMIC;
+INSERT INTO t1 VALUES(0,0);
+ALTER TABLE t1 ADD COLUMN c varchar(25)  DEFAULT NULL, ALGORITHM=INSTANT;
+UPDATE t1 SET c="" WHERE a=0;
+SELECT * FROM t1;
+a	b	c
+0	0	
+DROP TABLE t1;
 ############################################
 # Test instant ADD COLUMN for COMPACT format
 ############################################
@@ -121,3 +137,11 @@ a	b	d
 8	6	20
 10	1	10
 DROP TABLE t1;
+CREATE TABLE t1 (a INT, b INT) row_format=COMPACT;
+INSERT INTO t1 VALUES(0,0);
+ALTER TABLE t1 ADD COLUMN c varchar(25)  DEFAULT NULL, ALGORITHM=INSTANT;
+UPDATE t1 SET c="" WHERE a=0;
+SELECT * FROM t1;
+a	b	c
+0	0	
+DROP TABLE t1;

storage/innobase/rem/rec.h

@@ -507,7 +507,7 @@ static inline uint64_t rec_get_instant_offset(const dict_index_t *index,
   index->get_nth_default(n, &length);
 
   if (length == UNIV_SQL_NULL) {
-    return (offs | REC_OFFS_SQL_NULL);
+    return (offs | REC_OFFS_DEFAULT | REC_OFFS_SQL_NULL);
   } else {
     return (offs | REC_OFFS_DEFAULT);
   }