Re: Alter definition of a column

ksherlock(at)gmail(dot)com wrote:
> Hello,
>
> The +4 is for the overhead of a varchar field.
>
> Using ALTER TABLE <table> ALTER <field> TYPE VARCHAR(<newsize>) to
> change the size requires scanning the entire table. For large tables,
> this will be much slower than the pg_attribute query. Both will get
> the job done.
>

Thanks. Am I correct in assuming that this scanning of the entire
table is done when I use the 'ALTER TABLE' command and not something I
must do after it's done?

Thanks again for explaining it. I was thinking that the +4 had
something to do with overhead of some sort, but wanted to know for
sure.

Andy