From what I understand it's made to be used on Excel that is bidimensional.
Or not?
Probably it's a stupid question but it's my bachelor degree final exam and I'm getting paranoid
Dax is a multidimensional query language as MDX. So, definitively, it's not a bad idea. DAX has not been designed for Excel but for SSAS tabular. You use it from Excel to query your model in SSAS tabular or Power Pivot (Excel plug-in).
On the other hand, MDX is a bit more powerful but also a bit more difficult to write. If your query is relatively straightforward you could go for DAX.
At the end, between DAX and MDX, it will be just a question of are you familiar or not with this language.
PS: DAX is not supported on all versions of SSAS and is not supported by other Olap cubes
Related
Datalog is a lovely language for querying relational data. It is simple, clear, composes well, and supports recursive queries without additional syntax.
SQLite is a fantastic embedded database with what seems to be a powerful query engine able to handle recursive queries – see the examples at the bottom of that page for generating Mandelbrot sets and finding all possible solutions to Sudoko puzzles!
I'm interested to know if there is a fairly standard way to translate from a datalog query in to recursive SQL as supported by SQLite, or if there are libraries that provide this facility.
DLVDB is an interpreter for recursive Datalog that uses an ODBC database connection for their extensional data: http://www.dlvsystem.com/dlvdb/
Apart from that, the paper
S. Ceri, G. Gottlob, and L. Tanca. 1989. What You Always Wanted to Know About Datalog (And Never Dared to Ask). IEEE Trans. on Knowl. and Data Eng. 1, 1 (March 1989), 146-166. http://dx.doi.org/10.1109/69.43410
provides theoretical background and some pointers for translating Datalog into relational algebra.
I started using a graph database to store a big graph that im generating. But im not convinced as to why to use a graph database to do my job, and why not do what i want with a conventional RDBMS. My question in specific is, why is a Relational Database bad or rather Graph Database is BETTER than RDBMS to store graphs?
After reading Graph Databases (early release, available here: http://graphdatabases.com/) it all comes down to performance. Depending on how deep or recursive your query is, the longer it will take for your RDBMS or graph database to return results. Traditional RDBMS are not designed for the quick traversal of relationships between entities whereas graph databases are built specifically for this. This may not be an issue if your recursion is only 2 levels deep but after this level performance apparently degrades significantly.
Please take this with a grain of salt. This is coming directly from Graph Databases and I have not replicated these results.
I have a webstore which sells components (it is a academic project) which looks like this. I have developed the same web application using following database technologies:
MS Sql Server with Stored procedures and sql data reader
LINQ to Sql
DB4o using LINQ (Client/Server)
What features can I compare apart from the technical and theoretical details between relational database and object oriented database ?
It is my graduate/master's thesis final project. I want the features that i want to compare to be more practical and interesting so that I can draw some concrete and meaningful conclusions rather than abstract comparisons which don't create much interest and hard for inference.
Please help me.
Feel free to express your opinions.
Thanks in anticipation
PS: Don't downvote or flag this post, if some one doesn't like this question u may delete it after getting answered
Here is a site that compare DALs, maybe you can get some ideas for what other think you can compare.
http://ormbattle.net/
Also here is my first question on StackOverflow that I compare 4 dals for speed and optimization.
Benchmark Linq2SQL, Subsonic2, Subsonic3 - Any other ideas to make them faster?
What features can I compare apart
In you case I was try to compare the speed, and if the conversion to a DAL can give the same or more features that can get with out it. For example, can you get all the same questions that you can do direct with SQL or not, and what is the limitations.
Try creating some performance benchmarks and do a side-by-side compare of the three different DB technologies (these are not methodologies) for given types of queries.
I am evaluating a choice between Oracle OLAP and Pentaho Mondrian.
At the same time some people say that using a column DB could simply make the use of OLAP's redundant as they are much faster.
has anyone got any experience on the same.
Will it help if ou OLAP sits on a column db ?
OLAP is not about the storage only; it is about the MDX language as well. MDX is much more powerful than SQL to handle multi-dimensional (with hierarchical dimensions) queries.
You can have a look to www.icCube.com - it's pretty fast - I mean no problem to aggregate let's say 30 millions of facts over 20 dimensions in sub-seconds (without any pre-aggregation computation).
Columnar databases are truly designed for analytics. Beye Network published a series of blogs about columnar databases/when to use them. One of them can be found here: http://www.b-eye-network.com/blogs/mcknight/archives/2010/06/the_value_of_pe.php.
In full disclosure, I am the community manager for Infobright, an open-source Columnar database company. Pentaho and Infobright work very well together; in fact, there's a virtual machine with both Pentaho/Infobright installed. That VM can be downloaded on www.infobright.org.
Cheers and good luck,
Jeff
What is the easiest way to write user entered measure values (sales forcast) to the SQL Server Analysis Services OLAP cube from a .Net client application?
I'm aware that underlying fact table can be updated with DML statements and that cube can be reprocessed but I'm looking for alternatives.
Regards,
Aleksandar
We use pivot table Ranet OLAP for editing cube data.
View sample Simple PivotTable Widget - PivotTaple with Updateable
Writing updates to OLAP cube.
I nearly got into a project like this once. It did not go ahead, which I was very grateful for, after looking into the work involved. My advice to you is to run away!!!
You do not have to update actual cube data, or reprocess though - depending on how complex your user-entered data is going to be. I believe this is covered in Microsoft's standard MDX course, the notes of which you may be able to find online (sorry, I've since disposed of my copy). This depends on whether you want to learn MDX though, which is not easy.
I think you can use ADOMD .Net to do Writeback. You can ADOMDCommand to wrap UPDATE CUBE Statements.
ADOMD .Net
http://msdn.microsoft.com/en-us/library/ms123483(v=SQL.100).aspx
Link below talks about some of the issues in this approach, if you are doing too many updates together.
http://www.developmentnow.com/g/112_2006_1_0_0_677198/writeback-in-ADOMD-NET.htm