Re: Adding New Column with default value.

On Apr 28, 2025, at 1:24 PM, Gambhir Singh <gambhir.singh05@gmail.com> wrote:
> Row Count - 50 Billion

I've never dealt with a table that huge personally, but my concern would be that ALTER TABLE will lock the table for a
verylong time. Is this in a production environment with active usage of this table? Just SELECTs or are we talking
UPDATEsand INSERTs as well? If so, you might need to do something more complicated than just ALTER TABLE. 

If you have enough disk space in the storage area for this database to have two identical copies of this 50 billion row
table(with indexes!), you could make a copy of the table and either ALTER that copy or add the new column at the same
timeas making the copy and then, in a single transaction, rename the two tables to swap them. If you do it this way,
thenew table will replace the old table seamlessly without interrupting usage of the table. Somewhere in there, you
mightneed to re-sync the two tables to make sure any rows that got inserted or updated while you were making the copy
areincorporated into the new version of the table as well. 

Just some initial thoughts on how I would accomplish this and things I would consider when deciding how to do it.

Good luck,
Ed