CS-03 · Case study · Retail supply chain · Warehouse Execution System

Keeping warehouse stock and SAP in step

Sainsbury's · United Kingdom · 2023–25 · Role: IT Business Analyst

Aditya BankarAditya BankarSenior Business Analyst / Product Owner · 3 min read
~30%Less manual stock reconciliation effort
~15%Fewer stock discrepancies
Real-timeStock sync between WES and SAP
UKRetail supply chain and stores

The context

In grocery retail, the stock a system thinks you have and the stock on the shelf drift apart all the time. Every gap means extra counts, manual reconciliation and, in the end, empty shelves or waste.

At Sainsbury's I worked as an IT Business Analyst across retail supply chain, inventory management and store operations. My focus was the Warehouse Execution System (WES), the software that runs warehouse tasks, and how it shared stock data with SAP.

The problem

Walking the process with store and supply chain teams showed where accuracy was lost:

  • Stock figures in the WES and SAP did not always match, so teams could not fully trust either one.
  • Mismatches came to light late, often during stock counts.
  • Store and supply chain teams spent time reconciling stock by hand.
  • Recurring issues were fixed case by case instead of at the root cause.

My role

  • Ran process walkthroughs and user-journey mapping with store teams to see how workflows ran in practice.
  • Gathered and prioritised requirements with supply chain, store operations and IT teams.
  • Reviewed inventory and stock-accuracy reports with supply chain teams to trace recurring issues.
  • Documented as-is and to-be workflows, user stories and acceptance criteria.

The process, before and after

Each column is a team or system. Numbered badges point to where time was lost, or saved.

Scroll sideways to see the whole diagram →

Stock accuracy before: batch updates and manual reconciliationStore / warehouseWESSAPSupply chain teamStockmovesRecord movementin WESUpdate SAPin batches1Find mismatchduring counts2Reconcileby hand3Fixed,days later
  1. 1WES and SAP drift apart between batch updates.
  2. 2Mismatches come to light late, during stock counts.
  3. 3Teams reconcile stock manually, line by line.
Start Step Decision End Each column is one team or system. Arrows show hand-offs.

What changed, step by step

StepBeforeAfter
Stock update to SAPIn batchesIn real time
Finding mismatchesDuring stock countsFlagged as they happen
ReconciliationManual, line by lineOnly genuine exceptions investigated
Recurring issuesFixed case by caseTraced to root cause and fixed in the process

The approach

  1. 1
    Watch the workWalked the warehouse and store processes with the people doing them, and mapped each user journey.
  2. 2
    Find the recurring breakpointsUsed stock-accuracy reports with supply chain teams to see which mismatches kept coming back, and why.
  3. 3
    Define the redesignWrote requirements for WES workflows with real-time data sync to SAP, so both systems stay in step as stock moves.
  4. 4
    Turn breakpoints into backlogConverted each breakpoint into user stories with acceptance criteria and agreed the priority order.
  5. 5
    Document as-is and to-beGave supply chain and IT teams one shared picture of how the process worked before and after.

Sample work: user story

Story · WES-US-022

Flag stock mismatches between WES and SAP

As a supply chain analyst, I want stock differences between the WES and SAP to be flagged as soon as they appear, so that I fix real problems early instead of reconciling everything by hand.

Acceptance criteria

  • Given a stock movement is confirmed in the WES, when it is sent to SAP, then SAP shows the updated quantity for that location.
  • Given the WES and SAP quantities differ for a location, when the check runs, then the item is added to an exceptions list with both quantities and the difference.
  • Given an exception has been resolved, when the quantities match again, then the item leaves the exceptions list automatically.
  • Given an item appears on the list three times in a week, when the weekly report runs, then it is marked as a recurring issue for root-cause review.

Results

  • Manual stock reconciliation effort for store and supply chain teams cut by about 30%.
  • Contributed to a reduction of about 15% in stock discrepancies.
  • Workflow breakpoints turned into a prioritised WES backlog.
  • As-is and to-be documentation shared by supply chain and IT delivery teams.

What I learned

  • The fastest way to find a requirement is to watch the work being done.
  • Most stock accuracy problems are timing problems between systems.
  • Prioritise the breakpoints people hit every day, not the rare dramatic ones.

Internal system details are simplified. Diagrams are redrawn and all figures are approximate.