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https://issues.apache.org/jira/browse/MADLIB-1002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15342927#comment-15342927
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ASF GitHub Bot commented on MADLIB-1002:
----------------------------------------
Github user njayaram2 commented on a diff in the pull request:
https://github.com/apache/incubator-madlib/pull/49#discussion_r67965192
--- Diff: src/ports/postgres/modules/utilities/sessionize.py_in ---
@@ -35,41 +36,83 @@ def sessionize(schema_madlib, source_table,
output_table, partition_expr,
@param source_table: str, Name of the input table/view
@param output_table: str, Name of the table to store result
@param partition_expr: str, Expression to partition (group) the
input data
- @param time_stamp: str, Column name with time used for
sessionization calculation
+ @param time_stamp: str, The time stamp column name that is used
for sessionization calculation
@param max_time: interval, Delta time between subsequent events to
define a session
-
+ @param output_cols: str, list of columns the output table/view
must contain (default '*'):
+ * - all columns in the input table, and a new
session ID column
+ 'a,b,c,...' - a comma separated list of column
names/expressions to be projected, along with a new session ID column
--- End diff --
Processing strings will be error prone and adds a lot of complexity.
Nevertheless, this might be
a good to have feature. I will leave this as is for Phase 2 and look at it
in Phase 3.
Have added a comment in the Phase 3 JIRA
(https://issues.apache.org/jira/browse/MADLIB-1002).
> Sessionization - Phase 3 (minimum time)
> ---------------------------------------
>
> Key: MADLIB-1002
> URL: https://issues.apache.org/jira/browse/MADLIB-1002
> Project: Apache MADlib
> Issue Type: New Feature
> Components: Module: Utilities
> Reporter: Frank McQuillan
> Priority: Minor
> Labels: gsoc2016, starter
> Fix For: v1.9.2
>
>
> Story
> As a data scientist, I want to perform session reconstruction on my data set,
> so that I can prepare for input into other algorithms like path functions, or
> predictive analytics algorithms.
> This is a follow on to
> https://issues.apache.org/jira/browse/MADLIB-909
> https://issues.apache.org/jira/browse/MADLIB-1001
> to add minimum time.
> Details
> Add min time to the existing params:
> Proposed interface changes:
> {code}
> sessionize (
> source_table,
> output_table,
> partition_expr,
> order_expr,
> time_stamp,
> time_out,
> min_time, -- new
> output_cols,
> create_view
> )
> {code}
> where
> min_time (optional)
> Minimum delta time that must elapse for an event to be considered a valid
> event (default=0). If an event happens in less than min_time since the last
> valid event, it does not get included in the current session and is dropped.
> Same units as time_stamp.
> Implementation notes
> 1) Should be specified in the same units as the time_out parameter.
> 2) Always compare against the last valid session event, not against one(s)
> that just got dropped.
> For an example of how min_time could work, see Aster Analytics sessionization
> function [1].
> References
> [1] Aster Analytics users guide, see "sessionize" function
> http://www.info.teradata.com/edownload.cfm?itemid=143450001
> http://www.info.teradata.com/templates/eSrchResults.cfm?txtpid=&txtrelno=&prodline=all&frmdt=&txtsrchstring=aster%20analytics&srtord=Desc&todt=&rdSort=Date
> https://www.youtube.com/watch?v=C760M9ttK9Q
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