shutdown gracefully & single user mode?

hi, all experts there, greetings!

Just minutes ago, my boss found out one of the attributes in a
table is too short (varchar 64 for url), we need to make
it wider to 85 A.S.A.P. Seems that alter table can not do it.
So, I used pg_dump, (how to do it gracefully?) immediately drop the table,
shutdown the postmaster (not necessary?) and change the dumped table, and
then restart the postmaster, use pgsql to reload the data. Our database is
not large YET. So, it took ONLY 10 minutes to re-load.

the job was done. But I feel nervous -- because I expect this will
happen again SOON. What is the "standard" procedure for postgreSQL to
do such kind of things? more specifically (maybe there are some other
ways?):

1) how to shutdown postmaster gracefully (I simply used
kill proID. I feel lucky that I do not need to use -9 ! ) so
that I'm sure the data is not corrupted?
2) how to "shutdown"(drop) just one table gracefully?
3) any simpler way (alter-table-like) to widden the attribute?
4) single user mode?

thanks in advance!!!

amy

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