Oracle Express and RAMRAA

Oracle Express and RAMRAA

Post by Bouna BO » Tue, 05 Dec 2000 04:00:00



Hi,

Does any one get any information about RAMRAA ? Inconvients and
advantages of using this architecture ?

Thanks in advance.

 
 
 

Oracle Express and RAMRAA

Post by Chris McClella » Tue, 05 Dec 2000 04:00:00


The key thing with RAM/RAA - you MUST have your datawarehouse prebuilt, ands
the design is not allowed to change !!!

Good points - data (or the vast amount of it) is stored in the DW, but
accessed by Express on the fly
Bad points - bit slower than normal Express databases, obviously !

What did you want to know specifically ?

 
 
 

Oracle Express and RAMRAA

Post by Bouna BO » Fri, 08 Dec 2000 04:00:00


That's all what I want to know.

Thanks.

Chris McClellan a crit :

Quote:> The key thing with RAM/RAA - you MUST have your datawarehouse prebuilt, ands
> the design is not allowed to change !!!

> Good points - data (or the vast amount of it) is stored in the DW, but
> accessed by Express on the fly
> Bad points - bit slower than normal Express databases, obviously !

> What did you want to know specifically ?

 
 
 

Oracle Express and RAMRAA

Post by News » Wed, 20 Dec 2000 15:04:15


He forgot to mention that the peformance sucks!  One point to ponder, RAM
does a "where" clause which we all know is limited to 256 statements so they
break it up in multiple where clauses.  Bad design.  If you simply write a
cursor yourself, you can dynamically build a join where there's no limit and
it's very fast.

That's just the bug that's in it - that doesn't address the fact that you're
aggregating 100% of any Rolap access - if it's Molap, it's instantaneous
since there's no aggregation.  The Holap solution of course it optimal,
where you store any large volumes in relational and as much summary as
practical in Express.  This is the best of both worlds but requires some
design knowledge to make it work.  It's probably why Essbase doesn't do it
and Sqlserver only pretends to do it (it's half hearted attempt at it).

There are many horror stories where people used Ram and thought Express was
lousy product but they just don't realize that you can't wizard your way
into a well designed Olap solution (or any other for that matter).  If you
need advice in this area, try www.dwconsult.com - a very knowledgable group
of people who can advise you on best way to go.  As a client of theirs', I
highly recommend them.


Quote:> Hi,

> Does any one get any information about RAMRAA ? Inconvients and
> advantages of using this architecture ?

> Thanks in advance.

 
 
 

Oracle Express and RAMRAA

Post by Greg Loxto » Sat, 23 Dec 2000 20:08:18


Are you really suggesting that any tool analysing data from a relational
source containing base level data ONLY is going to be fast? Of course the
SQL created by Express is simple but this is because Express is designed to
extract and analyse small amounts of data - NOT report on huge volumes of
data requiring hefty and complex SQL statements. You state that MOLAP is
fast - but MOLAP is only fast because the data has been pre-aggregated. If
you performed your query against any MOLAP source which contained only the
base level data then this would also be slow (maybe not as slow as a
relational source, but slow it will be).

If you are making this sort of criticism, then I have two recommendations.
If you want reporting to be fast, create some summarisations in the
relational source. If you want to report on large volumes of data at the
lowest level then use an appropriate tool, not one designed for analysis.

HOLAP solutions can be good, but can also cause more problems than they
solve. Creating the correct summarisations in the relational source is often
much more efficient that moving the data into the MOLAP server - if the
summarisations are correct then the performance difference is minimal and
not worth the extra complexity and administration needed to build a HOLAP
solution.

You are right to point out that trying to implement anything in Express with
no multi-dimensional experience is a recipe for disaster. Unlike other
products such as MS Analysis Services and Essbase which do allow you to
build and run small models with an inappropriate design, Express is far less
tolerant of an inappropriate design. This is good in many ways as it ensures
that the appropriate design is created from the start of a project and will
scale and scale. I have heard stories about people creating 16 dimensional
models as a prototype, then wondering why the design doesn't work when they
try to put real data in. RAM is the same as any other OLAP solution - don't
try to do something stupid or something that the product isn't designed for,
then blame the product for being slow.

Greg Loxton
Rockport Software
www.rockportsoft.com


> He forgot to mention that the peformance sucks!  One point to ponder, RAM
> does a "where" clause which we all know is limited to 256 statements so
they
> break it up in multiple where clauses.  Bad design.  If you simply write a
> cursor yourself, you can dynamically build a join where there's no limit
and
> it's very fast.

> That's just the bug that's in it - that doesn't address the fact that
you're
> aggregating 100% of any Rolap access - if it's Molap, it's instantaneous
> since there's no aggregation.  The Holap solution of course it optimal,
> where you store any large volumes in relational and as much summary as
> practical in Express.  This is the best of both worlds but requires some
> design knowledge to make it work.  It's probably why Essbase doesn't do it
> and Sqlserver only pretends to do it (it's half hearted attempt at it).

> There are many horror stories where people used Ram and thought Express
was
> lousy product but they just don't realize that you can't wizard your way
> into a well designed Olap solution (or any other for that matter).  If you
> need advice in this area, try www.dwconsult.com - a very knowledgable
group
> of people who can advise you on best way to go.  As a client of theirs', I
> highly recommend them.



> > Hi,

> > Does any one get any information about RAMRAA ? Inconvients and
> > advantages of using this architecture ?

> > Thanks in advance.

 
 
 

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