Comments on: Star Schemas – to boldly go where no Excel spreadsheet has gone before

By: Death of the Star Schema? | Gobán Saor

Death of the Star Schema? | Gobán Saor — Thu, 19 Jan 2012 18:27:05 +0000

[...] from VBA – The CodeDeath of the Star Schema?HAMMERing away at Automated PowerPivot RefreshminimeStar Schemas – to boldly go where no Excel spreadsheet has gone before Theme: Coraline by Automattic. Blog at WordPress.com. /* */ var _qevents = _qevents [...]

By: Excel in Data | Gobán Saor

Excel in Data | Gobán Saor — Tue, 02 Nov 2010 17:44:49 +0000

[...] OLAP cubes, heavily influenced by the dimensional modelling technique commonly know as the star-schema, but with the presentational simplicity of the Excel’s PivotTable and an Excel-like [...]

By: Tom Gleeson

Tom Gleeson — Sun, 22 Aug 2010 09:07:57 +0000

Rob,

Yes this does appear to be the case which I’ll admit surprised me as I would have though the columnar nature of the Vertipaq engine would have compensated for the resulting wide rows of a flattened fact table. I think the main trick is, if you do denormalise something make sure the resulting additional attributes have the lowest cardinality possible i.e. don’t include high cardinality columns such as Order No, Address Line 1 etc.

I’ve not yet fully got my head around Vertipaq, it would be nice if MS published a bit more technical details about it. In the meantime we must depend of studies such as this http://sqlblog.com/blogs/marco_russo/archive/2010/02/04/table-denormalization-study-in-powerpivot.aspx and experiences of people like yourself in the field.

It also appears that a star schema design has processing advantages as well, obviously those who wrote and optimised the DAX/MDX to Veripaq queries had this data model as their primary use case.

Tom

By: powerpivotpro

powerpivotpro — Sun, 22 Aug 2010 03:59:52 +0000

Another HUGE benefit of star schemas over single flat tables in PowerPivot: compression. Compression is MUCH better in PowerPivot as you reduce the number of columns in your large tables. Storing all those extra attributes in your dimension tables, and only having a single (preferably integer) linkage column in the fact table can lead to dramatically smaller files.

Also, it should be noted that PowerPivot query performance is often (but not always) better as your compression rate improves. Smaller files also tend to result in faster queries. Star schemas – don’t leave home without ‘em

By: Micro ETL in the PowerPivot age « Gobán Saor

Micro ETL in the PowerPivot age « Gobán Saor — Fri, 20 Aug 2010 18:25:46 +0000

[...] quite likely a lot of the data you require will exist in the optimal PowerPivot import format, i.e. a star schema. You might be out of luck though as a significant percentage of DWs will not have used dimensional [...]

By: PowerPivot – Show Detail not allowed! « Gobán Saor

PowerPivot – Show Detail not allowed! « Gobán Saor — Tue, 17 Aug 2010 10:35:36 +0000

[...] Most of the commentary on PowerPivot has focused on its ability to handle really large datasets but this emphasis on ‘big-data’ (something the rest of the BI industry share) often ignores the power of human-scale small-data (i.e. the world of the spreadsheet jockeys). The power of a star-schema to model BI problems (be they small or large) is something I’ll return to in a later post. (UPDATE: http://blog.gobansaor.com/2010/07/09/star-schemas-to-boldly-go-where-no-excel-spreadsheet-has-gone-b...) [...]

By: Power (Pivot) to the People « Gobán Saor

Power (Pivot) to the People « Gobán Saor — Wed, 11 Aug 2010 15:22:06 +0000

[...] world from that perspective. I too could be accused of this bias with my previous post detailing the benefits of first creating a star schema before loading data into PowerPivot. For those of you from a business or pure spreadsheet [...]

By: Basic Data-Warehouse using Excel « Excel Tips Monster

Basic Data-Warehouse using Excel « Excel Tips Monster — Sat, 07 Aug 2010 21:50:27 +0000

[...] Gleeson explains, however, that with Microsoft’s new PowerPivot extension (and some work) you can create some pretty impressive data-warehouse functionality directly from Excel. Possibly related posts: (automatically generated)Power Pivot: Easy BI for [...]

By: Spreadsheet Add-Ins: Star Schemas in PowerPivot – Spreadsheet Day

Spreadsheet Add-Ins: Star Schemas in PowerPivot – Spreadsheet Day — Sat, 10 Jul 2010 14:04:14 +0000

[...] the Gobán Saor (Country Datasmith) blog, Tom Gleeson describes the role that Star Schemas play in PowerPivot, and outlines their advantages. First, he explains a Star Schema in simple terms as, "a [...]