database - OLAP Cube - Data Cube -

i have quick question regaring olap cubes or data cubes. when @ image not understand "where" represented data on cube is. guess 1 on surface, right? otherwise rotating cube not show different values.

so, question is, data stored "in cube?"

should not sth like:

f(x,y,z) -> value (1) 

and value inside cell? here see only

f(x,y) -> surfacevalue (2a)  f(x,z) -> surface value (2b)  f(y,z) -> surface value (2c) 

so, stored in cube? mappings (1 - 2c).

unfortunately, there lot of confusing terms connected olap databases. cubes 1 of worst offenders because applied databases, regardless of number of dimensions. despite fact might reasonably assume cube refers 3-dimensional object.

cube, in context, used metaphor , shouldn't considered literally. used because hard illustrate/imagine objects more 3 dimensions.

a 1-dimensional dataset represented this:

        10.00   15.00   16.00 -------------------------------- year    2014    2015    2017 

here can see measure plotted against year.

2-dimensions illustrated so:

region  1 |   5.00    2.00    4.00         2 |   5.00    5.50    5.00         3 |   0.00    7.50    5.00 ----------|-------------------------- year      |   2014    2015    2017 

now can see same measure plotted against year , region.

3-dimensions can thought of cube. wikipedia picture linked to example of this.

now higher dimensions examples hard/impossible generate on 2d screen. in practice 4/5/6/etc dimensional reports presented 2d report, series of filters applied, limiting returned records , totals.

example:

department:   marketing customer age: 18 - 24  region  1 |   1.15    1.50    0.00         2 |   2.75    4.01    1.25         3 |   0.00    0.00    1.14 ----------|-------------------------- year      |   2014    2015    2017 

this shows our measure 2 additional filters. 4d report.

the cube concept trying express there layers data, can navigate through.

dr rob meredith, of monash university, talks subject on 1 of podcasts. think it's half way through semester 1, 2009 - episode 3 or semester 1, 2009 - episode 4.