Understanding the Oracle Primavera P6 Scheduling Options

“Out of Sequence Progress” occurs when an activity starts before a predecessor defined by a relationship has finished. Therefore, the relationships have not been acknowledged and the successor activity has started out of sequence.

There are three options in P6 for calculating the finish date of a successor when the successor activity has started before the predecessor activity is finished:

• Retained Logic
• Progress Override
• Actual Dates

The selected option is applied to all activities in a schedule when it is calculated. Open the Schedule Options form by selecting Tools, Schedule… and clicking on the "Options" icon where the options are found under When scheduling progressed activities use.

Retained Logic

In the example following, the relationship is maintained between the predecessor and successor for the unworked portion of the activity (the Remaining Duration) and continued after the predecessor has finished. The relationship forms part of the critical path and the predecessor has no float.

NOTE: This is the recommended option.

Progress Override

In the example following, the Finish-to-Start relationship between the predecessor and successor is disregarded, and the unworked portion of the activity (the Remaining Duration) continues before the predecessor has finished.

NOTE: The relationship is not a driving relationship and DOES NOT form part of the critical path in the example and the predecessor has float.

Actual Dates

This function operates when there is an activity with Actual Start Dates in the future, which is not logical. With this option the remaining duration of an in-progress activity is calculated after the activity with actual start and finish in the future.

When there are no Actual Dates in the future this option calculates as Retained Logic.

In a properly updated schedule there should be no Actual Dates in the future. The situation with Actuals in the future may happen when two projects are opened together and have different Data Dates. This situation is best avoided, and it is best to make the Data Dates of all projects the same.

Retained Logic

In the example following, which has:

• Activity A1060 has Actual Start and Actual Finish dates in the future, which is not logical, the relationships to this task are ignored. Activities A1050 and A1070 are connected around this activity by retaining the logic.
• Activity A1020 has Actual Start and Actual Finish dates in the past, which is not logical, and the relationships to this task are ignored. Activities A1010 and A1030 are connected around this activity by retaining the logic.
• Activity A1030 is in progress and the activity is split. Activities A1010, the incomplete portion of A1020 and A1030 are connected by retaining the logic, but the complete portion of A1030 is ignored.

This method of calculation results in the most conservative result and the scheduler may change any logs if required.

Retained Logic with Looping logic

When a loop is inserted in the logic and the schedule is recalculated the loop is identified.

Progress Override

With Progress override:

• No logic is retained,
• Any task with a complete activity as a predecessor is ignored, and in turn
• Is scheduled on the Data Date

Progress Override with Looping logic

When a loop is inserted then the following issues are presented when scheduling:

• The Circular relationship is not identified and
• The schedule is recalculated, acknowledging the illogical looping logic.

Actual dates

When the option of Actual Dates is selected:

• A task with a complete activity as a predecessor has the predecessor relationship acknowledged;
• Negative float is calculated which should not happen when a schedule has no constraints

Note: This option should be avoided as there should never be completed tasks in the future and the Total Float is not calculated as expected.

Actual dates with Looping logic

When a loop in the log is introduced then:

• The Circular relationship is not identified;
• The schedule is recalculated, acknowledging the illogical looping logic;
• Negative float is calculated which should not happen when a schedule has no constraints.

Note: This option should be avoided as there should never be completed tasks in the future and the Total Float is not calculated as expected.

Discussion: There is a sound argument for the use of the Actual Dates option when there is a very large schedule that is being progressed over time. This option allows the scheduler to update activities that are in- progress or complete in the future and effectively give each activity its own approximate Data Date. The picture on the right shows how this works, but the down side of this process is that the Actual Duration for an in- progress activity may not be entered but a Physical % Complete may be entered.