Updating pg_attribute to widen column

[Justin Julicher <justin.julicher@xxxxxxxxx>]

Psql Version: 8.4

Hi,

 

We need to widen a column on a table with millions of rows and the only way to do this currently is to migrate the data from one column to another with a script and trigger.

 

I know how to do this via an update to pg_attribute which would incur the table scan penalty but I have a number of questions is – 

• Does postgres pick up this change straight away?
• Are there any caveats to my first question? 

thanks,

Justin