Cubes 1.1 release notes

These release notes cover the new features and changes (some of them backward incompatible).

Overview

This release brings major refactoring and complexity reduction of the SQL backend. Other notable changes:

  • implementation of arithmetic expressions
  • removal of all backends but SQL and Slicer into a separate packages
  • removal of all non-essential modules as extensions in separate packages

New Features

Model

  • changed all create_* methods into a model object class initializers from_metadata such as Cube.from_metadtata() or Dimension.from_metadata()

Cube:

  • Cube.base_attributes() - returns all attributes that don’t have expressions and are very likely represented by a physical column
  • Cube.attribute_dependencies() - returns a dictionary saying which attribute directly depends on which other attributes
  • Cube.collect_dependencies() - dictionary of all, deep dependencies (whole attribute dependency tree is expanded)

Attributes

Expressions

Attributes can now carry an arithmetic expression. Attributes used in the expressions must be other logical attributes. Only base attributes (those without expressions) require to have physical column mappings.

Example:

{“name”: “price_with_vat”, “expression”: “price * 1.2”}
{“name”: “price_with_discount”, “expression”: “price * (1 - discount / 100)”}

The expressions currently support basic arithmetics and few SQL functions. The expression language and operators are inspired (and will very likely follow) the Postgres SQL dialect, but is not going to be 100% compatible. Language will be extended gently, with regard to other backends or SQL dialects. (Note that the expression language is meant to be shared with other, non-Cubes tools).

Plugins

New plugin system. Packages can now advertise in their setup.py plugins:

..code-block:: python

entry_points={
‘cubes.stores’: [
‘my = my_package.MyStore’,

], ‘cubes.authorizers’: [

‘my = my_package.MyAuthorizer’,

]

}

Extensible obects: authenticators, authorizers, browsers, formatters, model_providers and stores.

Major Changes

Modules and Packages

The modules were restructured. The backend package was removed, it’s content was separated into external packages. sql became a top-level package, yet maintaining it’s optional status. It should stay in the Cubes package as it is the most used backend.

browser was split into two separate packages browser and cells.

New external packages:

  • cubes-ga
  • cubes-mongo
  • cubes-mixpanel
  • important: No longer generate implicit aggregates by default. Override in model

Model

  • Cube.all_attributes was changed to return actually all attributes of the Cube instead of just attributes for a fact table (non-aggregates). There are now three methods: Cubes.all_attributes(), Cubes.all_fact_attributes and Cubes.all_aggregation_attributes.

Model Attributes:

  • string representation of attributes now returns attribute reference instead of attribute name
  • ref is now a property of all attributes (originally it was a function ref(locale, simplify))
  • attribute reference is now opinionated without ability to have alternative way: all dimensions are simplified if they are flat and have no details, otherwise attribute reference is dimension.attribute
  • removed public_dimensions()

Other

  • removed store_name in Store
  • added Drilldown.natural_order

SQL

Now a top-level package as it will receive more attention in the near future. Simplified, made code more understandable and maintainable.

  • new SQL schema object holding information about the star/snowflake schema
  • topological sort of joins - joins are now ordered automagically, no longer cryptic exceptions about to-fact relationships
  • new QueryContext – replaces QueryBuilder
  • support for SQL Alchemy selectables as star/snowflake schema tables
  • removed simple vs. composed aggregation statement (which was required due to unpredictability of low-level mapping expressions), now every statement is just “simple” statement

Other:

  • find_dimension() and link_cube() are now global functions. Cube linking has been moved into the provider.
  • added naming convention dicitonary to the SQL mapper
  • added SQLSchemaInspector
  • SQLStore accepts metadata object
  • added compound keys (multiple columns) in joins

Fix:

  • if fact table schema is explicitly specified, use it in the joins as default schema

Slicer

The slicer command has been rewritten using Click. There are new commands and refreshed commands:

  • ext-info – list extensions and give more details about particuliar extension
  • materialize and aggregate – brought back under new sql command group
  • list – list cubes

The configuration slicer.ini is now as default and does not have to be explicitly provided if not necessary.

Removed

  • Dropped support for experimental “nonadditive” measures (temporarily)
  • Dropped support for experimental periods-to-date (requires specification)
  • Dropped support of experimental expr mapping (permanently)