insert after table modify bug

Hello!

I have found a transaction problem in 6.5.3. This is an example:

Begin;
create table a (a1 int4,a2 int4);
create table b (b1 int4);
alter table b add column b2 int4;
insert into b select * from a ;
ERROR:  INSERT has more expressions than target columns

The db sees new table b, but thinks it has only one column: if I try
"select * from b;" after the alter table command, I receive:
b1
--
(0 rows)

Moreover, I found another bug, but it seems it's the same as reported
Radhesh Mohandas at Feb, 4:

Begin;
Drop table a;
Drop table b;
-- now the second drop failed, e.g. table b doesn't exist - and I
-- want to roll back the whole transaction
rollback;

Table a "does" and "doesn't" exist: it cannot be created but every
select from a failes.

I found the only way how to fix the problem: delete these tables from
system tables, this means "delete from pg_class where relname='a'"
and then "delete from pg_type where typname='a'". Then execute vacuum,
which should, I think, synchronize indices. I tried it and it worked.

Don't you have anybody better solution?

Jan Urbanek