| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 185.1 | apples and oranges | SAGE::OISPG | Keith A: DESINE at ground zero | Tue Aug 30 1988 17:02 | 20 |
| I dont know DECIntact but doubtless an enthusiastic advocate will
jump in and tell you about it.
A point on relativity: products like ACMS, DECIntact are intended to be
TP monitors that layer over databases, operating systems, etc. Hence we
have to consider the definition of a "transaction" at each layer to see
what that layer gives us in terms of protection. For example, an ACMS
user may consider a certain activity to be one logical transaction but
Rdb may be given several Rdb transactions to do for that single logical
transaction. Rdb will look after each Rdb transaction but knows nothing
about the ACMS logical transaction. If Rdb transaction R1 may be
committed and then R2 will fail and be rolled back. This may cause
a failure for the ACMS logical transaction L1 but there is no way
(now) that Rdb nows that the previously committed R1 is invalid.
This difference in meaning between transactions is the reason for
discussion on 2 phase commit. Customers want a system where a high
level component (like ACMS, DECintact) can easily coordinate
transaction commits and rollbacks with lower levels like Rdb, RMS,
DBMS etc..
|
| 185.2 | Logical Transaction | CSTEAM::WADSWORTH | KIRBY WADSWORTH | Tue Aug 30 1988 23:06 | 6 |
| Thanks .1
As an old OLTPer, I view a transaction as a logical unit of work, not
an individual interaction with a database. If I transfer money
from my checking to savings, I want to be assured that the money
went into my savings account after it was successfully removed from
my checking account.
|
| 185.3 | I don't think that's why we have DecIntact | WIBBIN::NOYCE | Bill Noyce, Parallel Processing A/D | Thu Sep 01 1988 16:02 | 10 |
| DEC database products have provided transaction protection for a
long time: VAX DBMS V1 had it in 1981; VAX Rdb/VMS V1 in 1984.
RMS didn't have it until RMS Journaling (1987?). Intact was developed
to fill this hole in RMS (and also to add some other things (hashed
access?) that you probably know more about than I do). DEC decided
to buy Intact and re-sell it for reasons I don't entirely understand,
but I'm sure that it's partly because it appeared to provide much
better performance than ACMS did. I don't think it gives any more
transaction protection than are available in the database products
and (finally) now RMS.
|
| 185.4 | | CSC32::STENOISH | Jim Stenoish, VIA TBU, CSC/CS | Thu Sep 01 1988 20:23 | 7 |
| DECintact allows transaction integrity over multiple RMS databases,
something neither Rdb or DBMS currently allow. At the time DECintact
was acquired, ACMS had no transaction integrity if your database
wasn't all in 1 file Rdb or DBMS database. Of course, DECintacts
rollback/rollforward recovery facilities is not currently integrated
with Rdb's or DBMS' recovery facilities, so there doesn't seem to
be any advantage to using DECintact with Rdb or DBMS.
|