[ 
https://issues.apache.org/jira/browse/MADLIB-909?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Frank McQuillan updated MADLIB-909:
-----------------------------------
    Description: 
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.

Details

1)  The PDL Tools module sessionization module [1] is one example 
implementation.  Source code is located at [2].  Also see [7].

2) How to sessionize.  PDL Tools uses a time based session reconstruction that 
defines a session as a sequence of events by a particular user where no more 
than n seconds has elapsed between successive events.   That is, if we don’t 
see an event from a user for n seconds, start a new session.   The requirement 
for  MADlib is similar but with the following addition:
* generalize partition expression

3) Proposed interface:

{code}
sessionize (
   source_table,
   output_table,
   partition_expr,
   time_stamp,
   max_time)
{code}
where

output_table
add 2 new columns to the source_table:  session_id and new_session:
* session_id=1,2, ...n where n is the number of sessions in the partition

partition_expr
VARCHAR. The 'partition_expr' can be a single column or a list of 
comma-separated columns/expressions to divide all rows into groups, or 
partitions. Matching is applied across the rows that fall into t he same 
partition. This can be NULL or '' to indicate the matching is to be applied to 
the whole table.

time_stamp
Column name with time used for sessionize calculation

max_time
Delta time between subsequent events to define a sessions, i.e., session 
timeout.

Questions

1) Q: Do we need separate 'order_expr' and  'time_stamp' columns?  Aster does 
it this way.
A: No, we can't come up with a reason why a user would need this.  If we want 
to add later, we can add as an optional parameter.

2) Q: What to do if negative delta_t between events?
A: Do not include in session and output a warning message.

References

[1]  PDL Tools sessionization module
http://pivotalsoftware.github.io/PDLTools/group__grp__sessionization.html

[2] PDL tools source code
https://github.com/pivotalsoftware/PDLTools

[3] Blog on bot signatures from Akamai
https://blogs.akamai.com/2013/06/identifying-and-mitigating-unwanted-bot-traffic.html

[4] 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

[5] General information on sessionization
https://en.wikipedia.org/wiki/Session_(web_analytics)

[6] See path function for partition and order by params
http://madlib.incubator.apache.org/docs/latest/group__grp__path.html

[7] SQL sessionization example from blog
https://blog.pivotal.io/pivotal/products/time-series-analysis-1-introduction-to-window-functions

[8] Postgres example of SQL based sessionization
http://randyzwitch.com/sessionizing-log-data-sql/



  was:
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.

Details

1)  The PDL Tools module sessionization module [1] is one example 
implementation.  Source code is located at [2].

2) How to sessionize.  PDL Tools uses a time based session reconstruction that 
defines a session as a sequence of events by a particular user where no more 
than n seconds has elapsed between successive events.   That is, if we don’t 
see an event from a user for n seconds, start a new session.   The requirement 
for MADlib is similar but with the following addition:
* generalize partition and order expressions

3) Proposed interface:

{code}
sessionize (
   source_table,
   output_table,
   partition_expr,
   order_expr,
   time_stamp,
   time_out)
{code}
where

partition_expr
VARCHAR. The 'partition_expr' can be a single column or a list of 
comma-separated columns/expressions to divide all rows into groups, or 
partitions. Matching is applied across the rows that fall into t he same 
partition. This can be NULL or '' to indicate the matching is to be applied to 
the whole table.

order_expr
VARCHAR. This expression controls the order in which rows are processed or 
matched in a partition. For example, time is a common way to order partitions.

time_stamp
Column name with time used for sessionize calculation (often will be the same 
as order_expr but may not always be)

time_out
 Number of seconds between subsequent events to define a sessions.  Same units 
as time_stamp.

Acceptance

1) New test cases in install-check and TINC. TINC tests should include output 
validation tests (manually verified) and negative tests.
2) Updated documentation and online help functions (online help refers to the 
documentation that is accessible directly via SQL).
3) All tests should pass on Pulse.
4) Code should be independently reviewed and tested.

References

[1]  PDL Tools sessionization module
http://pivotalsoftware.github.io/PDLTools/group__grp__sessionization.html

[2] PDL tools source code
https://github.com/pivotalsoftware/PDLTools

[3] Blog on bot signatures from Akamai
https://blogs.akamai.com/2013/06/identifying-and-mitigating-unwanted-bot-traffic.html

[4] 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

[5] General information on sessionization
https://en.wikipedia.org/wiki/Session_(web_analytics)

[6] See path function for partition and order by params
http://madlib.incubator.apache.org/docs/latest/group__grp__path.html




> Sessionization - Phase 1
> ------------------------
>
>                 Key: MADLIB-909
>                 URL: https://issues.apache.org/jira/browse/MADLIB-909
>             Project: Apache MADlib
>          Issue Type: New Feature
>          Components: Module: Utilities
>            Reporter: Frank McQuillan
>            Assignee: Nandish Jayaram
>              Labels: gsoc2016, starter
>             Fix For: v1.9.1
>
>
> 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.
> Details
> 1)  The PDL Tools module sessionization module [1] is one example 
> implementation.  Source code is located at [2].  Also see [7].
> 2) How to sessionize.  PDL Tools uses a time based session reconstruction 
> that defines a session as a sequence of events by a particular user where no 
> more than n seconds has elapsed between successive events.   That is, if we 
> don’t see an event from a user for n seconds, start a new session.   The 
> requirement for  MADlib is similar but with the following addition:
> * generalize partition expression
> 3) Proposed interface:
> {code}
> sessionize (
>    source_table,
>    output_table,
>    partition_expr,
>    time_stamp,
>    max_time)
> {code}
> where
> output_table
> add 2 new columns to the source_table:  session_id and new_session:
> * session_id=1,2, ...n where n is the number of sessions in the partition
> partition_expr
> VARCHAR. The 'partition_expr' can be a single column or a list of 
> comma-separated columns/expressions to divide all rows into groups, or 
> partitions. Matching is applied across the rows that fall into t he same 
> partition. This can be NULL or '' to indicate the matching is to be applied 
> to the whole table.
> time_stamp
> Column name with time used for sessionize calculation
> max_time
> Delta time between subsequent events to define a sessions, i.e., session 
> timeout.
> Questions
> 1) Q: Do we need separate 'order_expr' and  'time_stamp' columns?  Aster does 
> it this way.
> A: No, we can't come up with a reason why a user would need this.  If we want 
> to add later, we can add as an optional parameter.
> 2) Q: What to do if negative delta_t between events?
> A: Do not include in session and output a warning message.
> References
> [1]  PDL Tools sessionization module
> http://pivotalsoftware.github.io/PDLTools/group__grp__sessionization.html
> [2] PDL tools source code
> https://github.com/pivotalsoftware/PDLTools
> [3] Blog on bot signatures from Akamai
> https://blogs.akamai.com/2013/06/identifying-and-mitigating-unwanted-bot-traffic.html
> [4] 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
> [5] General information on sessionization
> https://en.wikipedia.org/wiki/Session_(web_analytics)
> [6] See path function for partition and order by params
> http://madlib.incubator.apache.org/docs/latest/group__grp__path.html
> [7] SQL sessionization example from blog
> https://blog.pivotal.io/pivotal/products/time-series-analysis-1-introduction-to-window-functions
> [8] Postgres example of SQL based sessionization
> http://randyzwitch.com/sessionizing-log-data-sql/



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