Add constant properties for conversion metrics

[WilliamDee]

Change

Follow up on #352 by adding a new configuration constant_properties

constant_properties:
  - name: _string_ # optional.
     base_expr: _string_ # optional. Even if name above is expressed. defaults to name above. solves for role also
     conversion_expr: _string_ # same as base above

This allows users to specify properties to constant when calculating conversion metrics.

Example with Data

Suppose we hold a constant property session_id and we have an opportunity table (visits) and conversion table (buy) as follows,

VISITS
| date       | session_id  | user |
|:-----------|-------------|-----:|
| 2022-12-31 | s1          |    u1| <-- Successful conversion to BUY1
| 2023-01-03 | s2          |    u1| <-- Not a conversion (However, this would be a successful conversion if we didn't hold session_id constant as it is the closer than above to the BUY1 event)
| 2023-01-09 | s3          |    u2| <-- Not a conversion
| 2023-01-12 | s4          |    u2| <-- Successful conversion to BUY2

BUYS
| date       | session_id  | user |
|:-----------|-------------|-----:|
| 2023-01-05 | s1          |    u1| <-- BUY1
| 2023-01-13 | s4          |    u2| <-- BUY2

SQL Example

By adding a constant_property, we would append a new column reference to the partition by that and append a new AND condition to the join

SELECT
  distinct first_value(subq_0.ds) OVER (PARTITION BY subq_1.ds, subq_1.user_id, subq_1.constant_property ORDER BY subq_0.ds DESC) AS visit_ds
  , first_value(subq_0.user_id) OVER (PARTITION BY subq_1.ds, subq_1.user_id, subq_1.constant_property ORDER BY subq_0.ds DESC) AS visit_user
  , first_value(subq_0.referrer_id) OVER (PARTITION BY subq_1.ds, subq_1.user_id, subq_1.constant_property ORDER BY subq_0.ds DESC) AS visit_referrer_id
  , ...
  , subq_1.*
FROM {mf_test_session_state.mf_system_schema}.fct_visits subq_0
INNER JOIN {mf_test_session_state.mf_system_schema}.fct_buys subq_1
ON
  (
    subq_0.user_id = subq_1.user_id
  ) AND (
    subq_0.ds <= subq_1.ds AND subq_0.ds > subq_1.ds - INTERVAL 7 day
  ) AND (
    subq_0.constant_property = subq_1.constant_property
  )

[tlento]

See base PR, just annotating things.

[WilliamDee]

reopened in #916