Cubes 0.9.1: Ranges, denormalization and query cell

The new minor release of Cubes – light-weight Python OLAP framework – brings range cuts, denormalization with the slicer tool and cells in /report query, together with fixes and important changes.

See the second part of this post for the full list.

Range Cuts

Range cuts were implemented in the SQL Star Browser. They are used as follows:

Python:

cut = RangeCut("date", [2010], [2012,5,10])
cut_hi = RangeCut("date", None, [2012,5,10])
cut_low = RangeCut("date", [2010], None)

To specify a range in slicer server where keys are sortable:

    http://localhost:5000/aggregate?cut=date:2004-2005
    http://localhost:5000/aggregate?cut=date:2004,2-2005,5,1

Open ranges:

    http://localhost:5000/aggregate?cut=date:2010-
    http://localhost:5000/aggregate?cut=date:2004,1,1-
    http://localhost:5000/aggregate?cut=date:-2005,5,10
    http://localhost:5000/aggregate?cut=date:-2012,5

Denormalization with slicer Tool

Now it is possible to denormalize tour data with the slicer tool. You do not have to denormalize using python script. Data are denormalized in a way how denormalized browser would expect them to be. You can tune the process using command line switches, if you do not like the defaults.

Denormalize all cubes in the model:

$ slicer denormalize slicer.ini

Denormalize only one cube::

$ slicer denormalize -c contracts slicer.ini

Create materialized denormalized view with indexes::

$ slicer denormalize --materialize --index slicer.ini

Example slicer.ini:

[workspace]
denormalized_view_prefix = mft_
denormalized_view_schema = denorm_views

# This switch is used by the browser:
use_denormalization = yes

For more information see Cubes slicer tool documentation

Cells in Report

Use cell to specify all cuts (type can be range, point or set):

{
    "cell": [
        {
            "dimension": "date",
            "type": "range",
            "from": [2010,9],
            "to": [2011,9]
        }
    ],
    "queries": {
        "report": {
            "query": "aggregate",
            "drilldown": {"date":"year"}
        }
    }
}

For more information see the slicer server documentation.

New Features

• cut_from_string(): added parsing of range and set cuts from string; introduced requirement for key format: Keys should now have format "alphanumeric character or underscore" if they are going to be converted to strings (for example when using slicer HTTP server)
• cut_from_dict(): create a cut (of appropriate class) from a dictionary description
• Dimension.attribute(name): get attribute instance from name
• added exceptions: CubesError, ModelInconsistencyError, NoSuchDimensionError, NoSuchAttributeError, ArgumentError, MappingError, WorkspaceError and BrowserError

StarBrowser:

• implemented RangeCut conditions

Slicer Server:

• /report JSON now accepts cell with full cell description as dictionary, overrides URL parameters

Slicer tool:

• denormalize option for (bulk) denormalization of cubes (see the the slicer documentation for more information)

Changes

• important: all /report JSON requests should now have queries wrapped in the key queries. This was originally intended way of use, but was not correctly implemented. A descriptive error message is returned from the server if the key queries is not present. Despite being rather a bug-fix, it is listed here as it requires your attention for possible change of your code.
• warn when no backend is specified during slicer context creation

Fixes

• Better handling of missing optional packages, also fixes #57 (now works without slqalchemy and without werkzeug as expected)
• see change above about /report and queries
• push more errors as JSON responses to the requestor, instead of just failing with an exception

Links

Sources can be found on github. Read the documentation.

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Submit issues and suggestions on github

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If you have any questions, comments, requests, do not hesitate to ask.