How did you check if the ALTER query ran in parallel or not post making the
table degree parallel?
Because sometimes you may see that ALTER itself is executing in serial but
the recursive sqls that do the update the column value from char(8) to
char(9) are running in parallel.
On Tue, Aug 23, 2022 at 3:05 PM yudhi s <learnerdatabase99@xxxxxxxxx> wrote:
Hi All, We have got an ALTER table modify column column in which we are
increasing the length of a column from char(8 byte) to char(9 bytes) as
below. The table holds ~100million rows. We are seeing in the long ops its
showing to take 4-5hrs of time and the message showing up as 'Table Scan'.
I think one way is to move the data to another table and then truncate this
table and modify the column and then move the table back using INSERT
APPEND.But we were trying to understand if there exists any other less
impact and faster approach like making it happen in parallel threads etc. I
tried making the table Degree to parallel-16, buty the ALTER is still
running in serial.
alter table tab1 modify COL1 CHAR(9 BYTE);
Regards
Yudhi
