MADlib v1.3

Release Date: 2013-October-03

New Features:

• Cox Proportional Hazards:
  • Added stratification support for Cox PH models. Stratification is used as
    shorthand for building a Cox model that allows for more than one stratum,
    and hence, allows for more than one baseline hazard function.
    Stratification provides two pieces of key, flexible functionality for the
    end user of Cox models:
    -- Allows a categorical variable Z to be appropriately accounted for in
    the model without estimating its predictive impact on the response
    variable.
    -- Categorical variable Z is predictive/associated with the response
    variable, but Z may not satisfy the proportional hazards assumption
  • Added a new function (cox_zph) that tests the proportional hazards
    assumption of a Cox model. This allows the user to build Cox models and then
    verify the relevance of the model.
• NULL Handling:
  • Modified behavior of linear and logistic regression to 'omit' rows
    containing NULL values for any of the dependent and independent variables.
    The number of rows skipped is provided as part of the output table.

Deprecated functions:
- Cox Proportional Hazard function has been renamed to 'coxph_train'.
Old function names ('cox_prop_hazards' and 'cox_prop_hazards_regr')
have been deprecated, and will be removed in the next major version update.
- The aggregate form of linear regression ('linregr') has been deprecated.
The stored-procedure form ('linregr_train') should be used instead.

Bug Fixes:
- Fixed a memory leak in the Apriori algorithm.