Re: Column type modification in big tables

On Thu, Aug 15, 2024 at 4:41 PM Lok P <loknath(dot)73(at)gmail(dot)com> wrote:

> Additionally , if we are okay with the 7.5hrs of down time , is my
> calculation/extrapolation of total time consumption based on a sample
> table, for direct alter, accurate? Because, in that case , I was thinking
> it's less complex and also less error prone to just do it in a single alter
> command rather than going for multiple steps of detach, alter, attach
> partition.
>

Well, it's meant to get you a ballpark figure, but yes, it seems as though
you will probably okay, But for something this critical involving
production downtime, I would try out the exact command and see how long it
takes on a test system. Restore a backup (you have backups I hope) or use
pg_basebackup to make a copy of your prod system somewhere.

Cheers,
Greg