Postgres SQL Web Page

Hello,

I have been trying to figure out from the Postgres SQL web pages the
answers to some *very* basic questions, namely:

1. Does Postgres SQL run a transaction redo log for recovery after a
system failure?
2. Does it allow log archiving for recovery after media failure?
3. Does it support row-level or page level locking?
4. Do read-only queries block writers? (i.e. does it have a
multiversioned archictecture?)
5. Does it handle data clustering?
6. What options does it have for controlling the way data is organized
on the disk?
7. How easy is it to alter tables?  Can you add/delete/rename/change the
type of table columns?
7. How well does it perform? Are there any benchmark results available?

If you would point me to the answers to these questions I would greatly
appreciate it.

Thanks,

  Mark Butler

--
Mark D. Butler         ( butlerm @ xmission.com )
Software Engineer
Epic Systems
662 North 100 East
Farmington UT 84025
(801)-451-4583