DAC Refresh dates

Refresh dates refer to the date of the last ETL process (the last time data was extracted from tables in a given database or loaded into tables in a given database). The DAC uses the refresh dates to determine whether to run the incremental load commands or to run full load commands and whether to truncate the target tables.

Refresh dates are tracked only for tables that are either a primary source or a primary target on tasks in a completed run of an execution plan. The DAC runs the full load command for tasks on which a table is a primary source or target if the refresh date against the table is null. When there are multiple primary sources, the earliest of the refresh dates will trigger a full load or an incremental load. If any one of the primary source tables has no refresh date, then the DAC will run the full load command.

Table shows the possible scenarios regarding refresh dates.

Table 12. Refresh Date Scenarios

Scenario	Table Type (in Tasks child tabs)	Refresh Date	Command DAC Will Use	Truncate Target Table?
1	Primary Source	Null	Full Load	Yes
	Primary Target	Null
2 (See note below)	Primary Source	Null	Full Load	No
	Primary Target	Not Null
3 (See note below)	Primary Source	Not Null	Full Load	Yes
	Primary Target	Null
4	Primary Source	Not Null	Incremental Load	No
	Primary Target	Not Null

• Scenario 2. When two or more source tables load into the same target table as separate tasks, the source table in the second task may have refresh date as null while the target may have a refresh date.
• Scenario 3. When a source loads into more than one target table in separate tasks, the refresh date may be null for the second target table while the source table may have refresh dates.