Why is the OV value in Snowflake table not the same as OV value in MDM?

Question

This issue was caused by two different crosswalks having the same creation date. The value from one crosswalk showed as OV in Reltio UI, and the value of the other crosswalk was reflected in Snowflake as the OV.

Following is the JSON for the master ID of the same record reflected in Snowflake.

Answer

For survivorship strategies LUD and OldestValue in some rare scenarios, OV calculation has limitations and can be unpredictable.
 

• LUD- Only the first crosswalk wins if many crosswalks have the same update date.
• OldestValue - Only the first crosswalk wins if many have the same creation date.

 
We can see inconsistent OV values between Snowflake and MDM in such cases. The OV values are not stored in DB; they are recalculated every time we send a GET request. As a result, some of the survivorship rules can randomly pick different OV values. 
 
For instance, when we use OldestValue and multiple crosswalks share the same creation date, the platform selects the first one returned by the database. 
 
In such situations, we recommend to enable Advanced Survivorship Strategies in physical configuration:

"survivorshipAdvancedBehavior": [
        "LUD",
        "OldestValue",
        "OtherAtrributeWinnerCrosswalk",
        "SRC_SYS"
    ],

 

The OV calculation changes when survivorshipAdvancedBehavior is introduced:

• LUD - If some values have many crosswalks with the same most recent date, then all those crosswalks become winners, and all values with those crosswalks become winners.
• OldestValue - If some values have many crosswalks with the same oldest create date, then all of those crosswalks become winners, and all values with those crosswalks become winners.

If you cannot apply the advanced survivorship strategy, you must consider implementing a more specific fallback strategy. Currently, you have no fallback strategy for this attribute.
 

{
"attribute": "configuration/entityTypes/Organization/attributes/MasterID",
"survivorshipStrategy": "OldestValue"
},

 
If no fallback strategy is defined for an "OldestValue" survivorship strategy, the default fallback strategy applied is the "Last Update Date" (LUD) rule. This means that if the "OldestValue" strategy cannot determine a winner, the system will default to using the most recently updated value as the winner.  This will not help you here because the crosswalk came in simultaneously.

Resources

https://docs.reltio.com/en/objectives/resolve-potential-matches/potential-matching-at-a-glance/potential-matching-navigation/design-survivorship-rules/survivorship-rules

https://docs.reltio.com/en/objectives/resolve-potential-matches/potential-matching-at-a-glance/potential-matching-navigation/design-survivorship-rules/advanced-survivorship-strategies