Backend reliability engineering

The course, in order

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1. Keep a crawler from creating reservations

   Reject an unsafe state-changing use of a safe HTTP method before accepting any reservation effect.

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2. Reject an unsupported export representation early

   Reject an unsupported representation before acquiring or constructing an export body.

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3. Keep a supplied filter operator outside the query language

   Translate only allowlisted filter operators so caller values cannot extend the query language.

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4. Reject an unrelated site changing a cookie-authenticated record

   Validate the intended request origin before a cookie-authenticated mutation, rejecting ambiguous or unrelated origins.

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5. Keep a membership from outliving its missing owner

   Keep a stored membership tied to an existing owner through the actual relationship constraint.

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6. Prepare a remote quote without holding a scarce transaction

   Acquire a remote quote before opening the scarce local transaction that commits its checked result.

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7. Refuse a page cursor borrowed from another search

   Bind a continuation cursor to the original search scope rather than accepting a cursor borrowed from another query.

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8. Stop a two-account transfer from forming a lock cycle

   Acquire account locks in one shared ordering so two opposite transfers cannot form a lock cycle.

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9. Keep tenant scope on storage and cached results

   Include authenticated tenant scope in both storage lookup and cache identity.

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10. Decide a rollout from bad events in the declared window

    Evaluate the declared bad-event budget over the correct eligible window instead of an unrelated aggregate.

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11. Publish one validated configuration revision to every request

    Validate a complete configuration before atomically publishing one revision to every request owner.

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12. Choose the declared overflow policy without growing memory

    Apply the declared bounded-queue overflow policy without silently accepting an unbounded memory obligation.

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13. Spread a retry wave while respecting its cap

    Spread retry attempts under the stated jitter and cap policy without exceeding the permitted delay.

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14. Locate the slow minority hidden by an acceptable median

    Locate the slow minority in the supplied latency distribution instead of accepting a favorable median.

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15. Drain accepted work before releasing service resources

    Withdraw admission before draining accepted work and release service resources only after the owned drain settles.

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16. Keep an unvalidated upload outside the public object namespace

    Hold unvalidated uploaded bytes outside the public namespace and publish only a checked accepted object.

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17. Fence an old rollout coordinator after leadership changes

    Fence rollout publication to the current coordinator token so a replaced leader cannot overwrite accepted state.

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18. Report partial batch acceptance without pretending atomicity

    Report each independently durable batch result without claiming the whole batch committed atomically.

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19. Find a cross-row anomaly behind repeatable reads

    Recognize a cross-row write anomaly that repeatable individual reads alone do not prevent.

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20. Find the failed owner behind a chain of downstream symptoms

    Find the first failed fact owner in a dependency chain before treating downstream symptoms as independent causes.

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