I need to insert about 3.000.000 from one table into another.
The second table is empty and is newly created.
Undo tbsp consists of 4 files each starting at 1024 mb
with maximum size of 3072 mb.
The table current size
segment_name = 'TABLE_NAME'
group by segment_name
is 1280 mb.
Before insertion of new rows the UNDO tbsp was empty.
After the statemet
INSERT INTO TABLE2 SELECT * FROM TABLE1
was run the UNDO tbsp grew to nearly 800 MB in each of it's files and kept growing.
This is the only statement that's currently running on the database.
At the end the undo tbsp reached it's maximum size with the
error "Unable to allocate extent in tablespace UNDO_TBSP".
What can help me in this case?
Why undo tbsp takes more space than the table size?