Github user decibel commented on a diff in the pull request:
https://github.com/apache/incubator-madlib/pull/49#discussion_r67954746
--- 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 --
> We will have to decide if this is too hard a constraint to have or not.
> Having this constraint will take away all the messy string parsing stuff
> we currently have implemented though.
Yeah, I didn't realize what the code was doing. I think it would be nice
to allow the user to choose different output names if they want.
Perhaps a good compromise would be to detect ' AS ' in the string and
then treat it as a raw select clause. Another option would be to treat
an array as a list of columns and anything else as a select clause
(which would also support the * case, I think).
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