Processes (MRP and Supply Chain Planning Help)


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Processes

When executing the planning run, the above steps are carried out by one or more of the following seven processes:

Memory-based snapshot. This is the main Snapshot process. It is launched by the Launch Planning Process form. It's primary task is to prepare the list of planned items and perform the pre- and post-processing steps. Once it performs these steps, the memory-based snapshot behaves like a Snapshot Worker.

Snapshot monitor. This controls the rest of the planning process. It is launched by the memory-based snapshot and it in turn launches the snapshot workers, delete workers, loader workers, and the memory-based planner. The number of delete worker launched by the snapshot monitor is determined by the MRP:Snapshot Workers profile option. It launches the Delete Workers after it prepares the list of delete tasks (see Figure 45). The snapshot monitor also maintains a list of snapshot tasks and delete tasks and the current status of each task. It uses this list to provide the next snapshot task to the memory-based snapshot and snapshot workers. It uses the status of the delete tasks to determine if the flat files created by the memory-based snapshot and snapshot workers can be loaded into the database by the loader workers. The snapshot monitor is also responsible for ensuring the read consistency of the data captured by the memory-based snapshot and the snapshot workers.

Snapshot workers. The number of these workers launched by the snapshot monitor is based on the MRP:Snapshot Workers profile; setting the number to one makes the Snapshot run as a single-threaded process. The snapshot workers collect data on bills of material, work in process, on-hand quantities, purchasing, firm planned orders, routings and work in process job resource requirements. The snapshot monitor controls the snapshot workers and receives instructions on which tasks to perform next. The snapshot worker places the data into flat files and communicates the completion of the task and the file name to the snapshot monitor.

Snapshot delete workers. These workers are launched by the snapshot monitor and delete the planning data from the last planning run. Each worker reads MRP_SNAPSHOT_TASKS to get the next delete task. After it completes the delete, it updates the completion date in MRP_SNAPSHOT_TASKS.

Loader workers. The snapshot monitor launches one loader worker for each table requiring a load. The snapshot monitor launches the loader worker after the flat file for the snapshot data has been written and the last planning run data has been deleted. The loader worker uses SQL*Loader to load the data. The profile option MRP:Use Direct Load Option controls whether SQL*Loader uses direct loading or conventional loading methods.

Memory-based planner. The memory-based planner performs the gross-to-net explosion. Launched by the Snapshot Monitor or separately by the user, the memory-based planner loads the snapshot flat files into memory, nets the supply and demand for planned items and writes the output to flat files. These flat files are loaded into the database by loader workers.

Planner delete worker. This worker is launched by the memory-based planner. It runs only when the memory-based planner is run without the snapshot. It is responsible for deleting data from planner output tables, including MRP_RECOMMENDATIONS, MRP_GROSS_REQUIREMENTS, and MRP_FULL_PEGGING.

Figure 7-44 illustrates the Snapshot Monitor Process logic under the Memory-based Planning Engine. Below is a detailed explanation of the logic.

1. Launch X Snapshot Workers via the Concurrent Manager, where X is the number of Snapshot Workers to launch, as defined by the profile option MRP:Snapshot Workers.

2. Begin Snapshot Preprocessing. These tasks include calculating repetitive planning periods for all the planned organizations, and relieving the MPS.

3. List the items that the planning engine will include in the current run. The plan-level option Included Items determines this list.

4. The Snapshot Monitor launches Snapshot Delete Workers to clean old snapshot and planning output from the tables.

5. Snapshot Workers select data from system tables, including work in process, inventory, purchasing, and bill of materials and write the data to flat files. Since the data is written to flat files, the deletes are not a prerequisite for this step.

6. Loader Workers load the flat files from step 5 into the MRP snapshot tables.

7. Once the workers complete the list of items for planning, lock the tables if Snapshot Lock Tables is set to Yes, then ask the Snapshot and Snapshot Workers to set transaction to read-only.

8. Loop until the workers complete.

9. Snapshot post-processing begins, which consists of cleanup activities and the execution of user-defined Snapshot Tasks. After these steps, the Memory-based Planner performs the gross-to-net explosion and creates new supply orders.

If the user ran the Memory-based Planner without the Snapshot, the Memory-based Planning Engine launches Planner Delete Workers, which delete data from the planner output tables.

Processes

See Also