MDEV-20403 Assertion `0' or Assertion `btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIMESTAMP..ON UPDATE

remove a special treatment of a bare DEFAULT keyword that made it
behave inconsistently and differently from DEFAULT(column).
Now all forms of the explicit assignment of a default column value
behave identically, and all count as an explicitly assigned value
(for the purpose of ON UPDATE NOW).

followup for c7c481f4d91

3 files changed, 53 insertions, 3 deletions

diff --git a/mysql-test/r/default.result b/mysql-test/r/default.result
index c2de5a578f1..f4ef9fcc8c8 100644
--- a/mysql-test/r/default.result
+++ b/mysql-test/r/default.result
@@ -3372,7 +3372,7 @@ insert into t1 values (b, 5, '5 the value of the DEFAULT(a), that is b');
 select * from t1 order by t;
 a	b	t
 5	5	1 column is omitted
-5	5	2 column gets DEFAULT, keyword
+4	5	2 column gets DEFAULT, keyword
 4	5	3 column gets DEFAULT(a), expression
 4	5	4 also expression DEFAULT(0)+0
 4	5	5 the value of the DEFAULT(a), that is b
diff --git a/mysql-test/r/function_defaults.result b/mysql-test/r/function_defaults.result
index 1c63ae17a5d..4a8f64df352 100644
--- a/mysql-test/r/function_defaults.result
+++ b/mysql-test/r/function_defaults.result
@@ -3116,3 +3116,32 @@ select if(@new = j, 'correct', 'wrong') from t1;
 if(@new = j, 'correct', 'wrong')
 correct
 drop table t1;
+create table t1 (a int, b varchar(20) default 'foo');
+insert t1 values (1,'bla'),(2, 'bar');
+select * from t1;
+a	b
+1	bla
+2	bar
+update t1 set b=default where a=1;
+select * from t1;
+a	b
+1	foo
+2	bar
+drop table t1;
+create table t1 (
+a int,
+b timestamp default '2010-10-10 10:10:10' on update now(),
+c varchar(100) default 'x');
+insert t1 (a) values (1),(2);
+select * from t1;
+a	b	c
+1	2010-10-10 10:10:10	x
+2	2010-10-10 10:10:10	x
+set timestamp=unix_timestamp('2011-11-11 11-11-11');
+update t1 set b=default, c=default(b) where a=1;
+select * from t1;
+a	b	c
+1	2010-10-10 10:10:10	2010-10-10 10:10:10
+2	2010-10-10 10:10:10	x
+drop table t1;
+set timestamp=default;
diff --git a/mysql-test/t/function_defaults.test b/mysql-test/t/function_defaults.test
index 1e3e86599e3..dd3ba109b2a 100644
--- a/mysql-test/t/function_defaults.test
+++ b/mysql-test/t/function_defaults.test
@@ -24,14 +24,14 @@ source 'include/function_defaults.inc';
 # MDEV-20403 Assertion `0' or Assertion `btr_validate_index(index, 0)' failed in row_upd_sec_index_entry or error code 126: Index is corrupted upon UPDATE with TIMESTAMP..ON UPDATE
 #
 
-# ON UPDATE DEFAULT NOW and indexed virtual columns
+# ON UPDATE NOW and indexed virtual columns
 create table t1 (t timestamp, i int, v timestamp as (t) virtual, key(v));
 insert t1 (t,i) values ('2006-03-01 23:59:59',1);
 update t1 set i = 2;
 check table t1;
 drop table t1;
 
-# ON UPDATE DEFAULT NOW and triggers
+# ON UPDATE NOW and triggers
 create table t1 (t timestamp, i int);
 create trigger tr1 before update on t1 for each row set @new:=new.t;
 insert t1 (t,i) values ('2006-03-01 23:59:59', 1);
@@ -46,3 +46,24 @@ insert t1 (i) values (1);
 update t1, t1 as t2 set t1.i = 2;
 select if(@new = j, 'correct', 'wrong') from t1;
 drop table t1;
+
+# SET xxx=DEFAULT
+create table t1 (a int, b varchar(20) default 'foo');
+insert t1 values (1,'bla'),(2, 'bar');
+select * from t1;
+update t1 set b=default where a=1;
+select * from t1;
+drop table t1;
+
+# ON UPDATE NOW and SET xxx=DEFAULT
+create table t1 (
+  a int,
+  b timestamp default '2010-10-10 10:10:10' on update now(),
+  c varchar(100) default 'x');
+insert t1 (a) values (1),(2);
+select * from t1;
+set timestamp=unix_timestamp('2011-11-11 11-11-11');
+update t1 set b=default, c=default(b) where a=1;
+select * from t1;
+drop table t1;
+set timestamp=default;