On Thu, 3 Dec 2020, Michael Lewis wrote:
On Wed, Dec 2, 2020 at 11:53 PM charles meng <xlyybz@xxxxxxxxx> wrote:
I have a table with 1.6 billion records. The data type of the primary key column is incorrectly used as integer. I need to replace the type of the column with bigint. Is there any ideas for this?
You can add a new column with NO default value and null as default and have it be very fast. Then you can gradually update rows in batches (if on PG11+, perhaps use do script with a loop to commit after X rows) to set the new column the same as the primary key. Lastly, in a transaction, update any new rows where the bigint column is null, and change which column is the primary key & drop the old one. This should keep each transaction reasonably sized to not hold up other processes.
Tell me, please, why ALTER TABLE <tablename> ALTER COLUMN <columnname> SET DATA TYPE BIGINT will not do the job? I've found some varchar columns in a couple of tables too small and used the above to increase their size. Worked perfectly. Regards, Rich
