The Difference Between Meta_last_mod_date and Source_timestamp in MDC

Reported for version 10

What is the difference between meta_last_mod_date and source_timestamp columns in MDC?

source_timestampis an MDC internal column introduced in version 10. It represents the point in time when a particular record has changed (in a source system). We use this information to compare similar records in MDC, for example, when a long batch runs and a quick online RW request is called on the same record. It is an optional attribute. If it is not provided, MDC uses now()function during the loading of the data.

meta_last_mod_date is a column defined in the CDI example project metadata. It was introduced into the metadata in V9 and used in a similar way as  source_timestamp - to track the timestamp when a record was created (or its relevant business date). Once source_timestamp was introduced in V10 as an internal engine column, the two columns essentially acted as duplicates leading to the removal of meta_last_mod_date in MDC v10.3.0 release.  
You can find a complete list of MDC internal columns on our documentation page.