Understanding the vital constraints that dictate exactly *when* an item is replenished.
Beyond the Math
In the previous post on Replenishment Fundamentals, we discussed the math: how RMS calculates if we need stock and how much we need.
However, even if the math says a store needs 50 units of Coca-Cola today, RMS might not generate an order. Why? Because the Replenishment Attributes dictate the timing constraints. RMS must consider:
- Are we allowed to review this item today?
- If we order it today, can the supplier deliver it?
- How long will it take to arrive?
Review Cycles
A Review Cycle dictates the specific days of the week that the replenishment batch (reqext.pc) is allowed to evaluate an item/location combination.
If an item's review cycle is set to only Monday and Thursday, and today is Tuesday, the replenishment batch will completely skip the item—even if its inventory is at zero.
Why use Review Cycles?
Without review cycles, RMS would generate tiny, fragmented orders every single day. By restricting reviews to specific days, you consolidate orders into larger, more cost-effective shipments that hit supplier minimums.
Delivery Schedules
A Delivery Schedule defines when a location is physically capable of receiving a delivery. For example, a mall-based store might not be allowed to receive deliveries on weekends, or a specific supplier might only dispatch trucks on Wednesdays.
RMS uses the Delivery Schedule to calculate the Next Delivery Date.
How it works together:
- Today is Monday. RMS reviews the item (because Monday is on the Review Cycle).
- The item needs 100 units.
- The Lead Time is 2 days.
- If ordered today (Monday), the truck will arrive on Wednesday (Monday + 2 days).
- RMS checks the Delivery Schedule. Can the store receive on Wednesday?
- If YES: The order is placed.
- If NO: RMS looks for the next available delivery day (e.g., Thursday). It then calculates if the store will run out of stock before Thursday. If so, it might order earlier, or hold the order until Tuesday to meet the Thursday delivery.
Lead Times
Lead Time is the expected duration between the creation of the Purchase Order (or Transfer) and the physical receipt of the goods.
RMS tracks multiple types of lead times:
- Supplier Lead Time: Found on
ITEM_SUPP_COUNTRY_LOC. The expected time for a vendor to ship to a DC or store. - Transfer Lead Time: Found on the routing tables. The expected time for a DC truck to reach a store.
Protection Level
During the lead time, the store will continue to sell inventory. RMS calculates a "Protection Level" (Forecasted Daily Sales × Lead Time) to ensure the store doesn't run out of stock while waiting for the truck to arrive.
Key Tables
Let's look at where these attributes are stored in the database.
| Column | Type | Description |
|---|---|---|
REPL_ITEM_LOCPK | Table | Contains the base review cycle code and delivery schedule code for the item/location. |
DELIVERY_SCHEDULEPK | Table | Defines the specific days of the week (Sunday-Saturday flags) a delivery can occur. |
REVIEW_CYCLEPK | Table | Defines the specific days of the week an item can be reviewed. |
ITEM_SUPP_COUNTRY_LOC | Table | Stores the specific lead time (in days) for a given supplier delivering a specific item to a specific location. |
Key Takeaways
- Replenishment math is constrained by time: Review Cycles, Delivery Schedules, and Lead Times.
- Review Cycles prevent fragmented ordering by batching evaluations to specific days.
- Delivery Schedules ensure orders are only created for days the location can physically receive them.
- Lead time dictates the "Protection Level" needed to survive until the truck arrives.
