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Conference ulysse::rdb_vms_competition

Title:DEC Rdb against the World
Moderator:HERON::GODFRIND
Created:Fri Jun 12 1987
Last Modified:Thu Feb 23 1995
Last Successful Update:Fri Jun 06 1997
Number of topics:1348
Total number of notes:5438

1169.0. "Rdb & ORACLE on same System" by FHOPAS::BREWMN::BREWIS () Wed Jul 08 1992 18:59

I have a customer who is considering purchasing Rdb.
They currently have ORACLE everywhere on all their systems.  The customer would
like to know of any observations we have made, either empirical or casual, that
would provide some feedback as to how the ORACLE and Rdb applications performed 
on the system.  

Was there anything that caused the two databases to trip over
one another?  Did one db or application seem to be extremely effected by the
load?  Other observations?

Another part of their question was:

	In Digital's opinion (always a dangerous question to answer when started
	in this manner :-) ), if I have a system with 10 ORACLE applications
	and I want to add 5 more applications on that same system, which would
	be the better approach in terms of providing better performance and less
	overhead on the system?   Use ORACLE for the 5 new apps with the 
	knowledge that I shouldn't expect much more ORACLE overhead because I
	have already taken the hit with the existing 10 apps?  Or, use Rdb and
	incur additional overhead for something that wasn't on the system 
	before with the hope that Rdb performs better and the increased overhead
	is negated by better performance overall?

Thanks,

Rick
T.RTitleUserPersonal
Name		DateLines
1169.1Hard to answerTRCOA::MCMULLENKen McMullenWed Jul 08 1992 21:0117
    Rick,
    
    Your question is almost impossible to answer, because it is not as
    simple as the picture you have painted. 15 Oracle apps versus 10 Oracle
    apps + 5 Rdb apps : what does this mean? Does each application have its
    own database or shared databases; what was the application developed in;
    what are the usage patterns???????????? Are there any needs for sharing
    data between applications? Do all applications run at the same time.
    
    One thing you will need more of in the mixed environment is memory and
    disk due (need to install both products). Why is your customer
    considering the migration? They will have some training and management
    issues in the mixed environment. Backups, database tuning, 4GLs,
    databse creation will be different in both worlds (ie knew DBA skills
    will be required). If he is worried about a little extra
    overhead (if any) in a mixed envrionment, then I would question why
    they are interested in Rdb.
1169.2Hard to ask too ;-)FHOPAS::BREWMN::BREWISThu Jul 09 1992 00:2938
Ken,

Thanks for your response.  It was a hard question to ask.  I realize that
any question around db and application performance is very difficult to answer
because there are so many factors involved like:
	. Application design (or lack of)
	. system load
	. resource constraints (cpu, mem, disk)
	. fragmentation and extents
	. long transactions  
	.....

So, my questions were meant to be of a more generic nature even though I 
provided a specific example.

I guess what I really would like to hear from folks is if they have seen any
Rdb/ORACLE installations and what were the observed impacts.

Also, were there any problems with the interaction of the two?  For example, 
did Rdb's use of DLM interfere with how ORACLE used it?  Or did ORACLE use or 
abuse of some other piece of VMS cause Rdb to do funny things?

Additionally, I think that there may be some folks out there that might be
able to comment on the "overhead" aspect of the base note.  Is ORACLE 
architected such that it really wouldn't use that much more of the system?

To answer your question about why would they want to use Rdb and ORACLE if they
are concerned about a little extra overhead.  They are considering a possible
move towards Rdb and away from ORACLE.  If they do it, they won't do it all at
once and it will have to be on existing machines that already have ORACLE on it.
They will also move to Rdb gradually so as to ensure that they feel comfortable
users are effected minimally.  They have 22 plants around North and South 
America running ORACLE today and about 700 person-years of investment in ORACLE
db and application development.  So, it is advisable to move cautiously.

So, keep those cards and letters coming.

Rick
1169.3O used high prioritiesGRANPA::KMCGINNISAsk me about my Rdb serverThu Jul 09 1992 16:218
    A few years back, I helped develop an Rdb application for a customer
    that had Oracle running on the target system.  Oracle interfered with
    the Rdb application in the following way:  The detached processes that
    did the actual database access for the Oracle users ran at an elevated
    priority and would prevent our Rdb users from getting their fair share
    of cpu cycles.
    
    Ken
1169.4O still run with higher priorities today?FHOPAS::BREWMN::BREWISThu Jul 09 1992 23:5311
Ken,

Thanks for the info.

Does anyone know if the ORACLE database server processes still run at an 
elevated priority?  Is this one of the recommendations ORACLE makes for improved
database performance?

What else has anyone observed?

Rick
1169.5ORACLE process prioritiesPRMS00::LOERICHLurch here! You rang?Fri Jul 10 1992 18:3616
>Does anyone know if the ORACLE database server processes still run at an 
>elevated priority?  Is this one of the recommendations ORACLE makes for improved
>database performance?

I remember there being a reference in the `ORACLE VAX/VMS Installation Guide'
about priority settings for ORACLE processes.  I think that it said those
processes should not run at a priority higher than an interactive user.
Unfortunately, I don't have the documentation handy to verify that.

In my limited experience, ORACLE and Rdb/VMS did peacefully co-exist.  The
application was primarily Read-Only from ORACLE and Read-Write to and from
Rdb/VMS.

Kathleen Loerich