RE: [Sanchez-gtm-core] Mumps comments

[K.S. B. <k.b...@sa...>]

On Sunday, November 19, 2000 at 15:49:49 (GMT+0100), Emiliano wrote:
 > K.S. Bhaskar wrote:
 > 
 > > To be complete, I should add that although GT.M is a heavy duty transaction
 > > processing database engine, one feature missing from GT.M is support for two
 > > phase commit.  This is being considered for the future, but won't happen
 > > anytime soon (basically, we haven't yet figured out how to add it without a
 > > significant impact on performance).
 > 
 > I'm really a database newby. I don't know what a two-phased commit is.
 > Does that mean you can have multiple changes withing one transaction?
 > No, that can't be it. Please enlighten me.

GT.M has full ACID properties if it is the only transaction processing
database engine.

Two phase commit applies if there are multiple database back ends.
Suppose there are two databases, say customer information kept in an
LDAP server not written in GT.M (actually, GT.M would be a great
database for an LDAP server, but that's another soapbox for another
day) and banking information kept in PROFILE/Anyware, which runs on
GT.M.  Let's say you want to create a customer record, and a checking
account as one transaction that must either be committed to all
databases or not be committed to any database.  The first part of a two
phase commit is to verify that each database can commit the transaction
and the second phase is to tell each database to commit it.

-- Bhaskar