LESSON 3 — The DBA Evidence-First Workflow (Your Professional System)

Many beginners “guess.” Real DBAs measure first.

The 6-step evidence-first workflow

Step 1: Define the symptom (what is happening?)

Examples:

• “Checkout page is slow”

• “Report takes 3 minutes”

• “Users can’t log in”

• “Database is full”

Write the symptom clearly. Do not jump to the solution yet.

Step 2: Measure (collect evidence)

Evidence is objective. Examples:

• Wait stats show I/O waits

• Blocking chain shows one session blocking many

• Query Store shows a plan regression after deployment

• Error log shows repeated failures

Step 3: Isolate the cause (what type of problem is it?)

Most production issues fall into these buckets:

• CPU pressure (too many expensive queries)

• I/O pressure (slow disk reads/writes)

• Memory pressure (insufficient memory, spills, poor cache)

• Blocking/deadlocks (concurrency issues)

• Bad plan/regression (optimizer chose a worse plan)

• Configuration (MAXDOP, memory settings, tempdb setup)

Step 4: Change safely (small, reversible changes)

Safe first moves:

• capture evidence

• stop the bleeding (short-term workaround)

• apply a targeted change with rollback

Unsafe moves:

• “Let me rebuild everything”

• “Let me change 10 settings at once”

• “Let me restart production”
  (These can cause outages.)

Step 5: Validate (prove it worked)

Validation must be measurable:

• response time improved

• CPU dropped

• blocking reduced

• error stopped repeating

• no new errors introduced

Step 6: Document (so it never happens the same way again)

Your documentation is part of the fix:

• what happened

• what evidence you saw

• what you changed

• why you changed it

• how you validated

• prevention plan

Example: “The system is slow”

Bad approach:

• “I’ll rebuild indexes and hope it fixes it.”

Professional approach:

1. Define: “App queries slow since 9:05 AM.”

2. Measure: “Many sessions waiting on locks.”

3. Isolate: “Blocking chain caused by one long transaction.”

4. Change: “Coordinate with app owner, end blocker, reduce transaction scope.”

5. Validate: “Response returns to normal, blocking clears.”

6. Document: “Incident summary + prevention steps.”

Try it now (10 minutes):
Write your own 6-step workflow in your DBA Notebook using a made-up incident:

• “A report is slow”

• “A restore is needed”

• “A login fails”
  Choose one and fill all 6 steps.