Enable DynamoDB Global Tables

DynamoDB Global Tables is a way of keeping a copy of a database table running and writable in more than one AWS Region at the same time, so the application survives an entire Region going down and serves users in distant geographies quickly. It is genuinely valuable for the workloads that need it — but it is not free, and it is not a setting you want switched on everywhere by default. Turning it on for a table roughly multiplies that table's running cost by the number of Regions it's copied into.

The cost shows up in three places on the invoice. Every write now happens in each Region, and the replicated writes are billed separately in each replica Region — two Regions means you're paying for the write twice. Storage is charged in full in every Region, because each replica holds a complete copy of the data. And the replication traffic between Regions is billed as cross-Region data transfer. So a single-Region table that costs, say, $4,000 a month can land closer to $8,000-$9,000 a month once it's replicated to a second Region. That's a real, recurring increase, not a one-time setup fee.

The right way to frame this for budgeting is as insurance with an ongoing premium, weighed against the cost of an outage. For a revenue-critical table where a Region failure means lost sales or a contractual SLA breach, doubling the table's cost to remove that risk is an easy trade. For an internal table, a reporting table, or anything where a few hours of recovery from backup is acceptable, the cheaper and correct answer is usually a single Region with point-in-time recovery and AWS Backup. The question to ask engineering is never "why isn't this on?" — it's "does this specific table need to survive a Region failure, and is that worth roughly doubling its cost?"

Dana is the finance partner embedded with the payments platform team. Engineering brings a request to enable Global Tables on the wallet-balances table for disaster recovery. The single-Region table costs about $5,200 a month; the proposal will take it to roughly $10,000 a month — a permanent ~$58,000-a-year increase. Dana's job isn't to approve or block on the dollar amount alone; it's to make sure the trade is deliberate.

She asks three non-technical questions. First, what specifically does this protect — what happens to revenue or compliance if this exact table is unavailable for a few hours? The answer is a contractual 99.99% SLA on a service that processes live transactions, with penalty clauses; an outage isn't just lost sales, it's a breach. Second, is there a cheaper option that would be acceptable — would point-in-time recovery and a backup restore meet the requirement? For a payments balance table the answer is no; hours of recovery time is not acceptable. Third, is this the only table that needs it, or is this the start of a pattern? Engineering confirms it's a deliberate, short list of revenue-critical tables, not a blanket policy.

With those answers, the $58k/year is easy to defend: it's insurance priced well below the cost of a single SLA-breaching outage, applied only where it's needed. Dana adds the replicated-table cost as a named line on the cost pack so it stays visible, and sets a standing rule that any new Global Table needs the same three-question justification before it's switched on. The discipline isn't to minimise the spend — it's to make sure every dollar of it maps to a table that genuinely needs to survive a Region failure.

The direct line-item impact of enabling Global Tables is large and recurring: roughly the table's write-and-storage cost again for each additional Region, plus cross-Region transfer. A $5,000-a-month table becomes a $10,000-a-month table the day a second Region is added, and stays there. That's not a rounding error — for a handful of high-traffic tables it can be a five-figure monthly swing. So unlike most cost findings, the risk here is over-correction: a well-meaning "turn it on everywhere for safety" decision can balloon the DynamoDB bill with no business justification.

Weighed correctly, though, the spend is insurance against a quantifiable outage cost. The right framing for the cost pack is to put the doubled table cost next to the cost of the outage it prevents — lost transaction revenue per hour, SLA penalty clauses, reputational cost. For a payments or checkout table those numbers dwarf the replication premium and the decision is trivial. For an internal table they don't, and the cheaper single-Region-plus-backup design is the correct financial answer. The job is to make sure each enablement is tied to a specific outage cost, not a general feeling of safety.

There's a forecasting angle too. Because the current Global Tables version bills replicated writes on the same on-demand or provisioned meter as normal writes, the extra cost doesn't appear as a tidy separate line — it shows up as the table's write and storage cost simply being larger in two Regions. That makes it easy to miss in variance analysis. Tag or name replicated tables explicitly so the multi-Region premium is visible and attributable, rather than buried in aggregate DynamoDB spend.

Finally, treat the count of Global Tables as a governance metric, not just a cost line. A slowly growing number of replicated tables with no corresponding list of business justifications is a sign that multi-Region is being switched on by reflex. The healthy state is a short, stable, named list of revenue-critical tables — each one defensible — not an ever-expanding set chosen table-by-table by individual engineers.

DynamoDB Global Tables keeps a critical database live and writable in more than one AWS Region simultaneously. If an entire Region fails, the business keeps running with effectively no data loss and recovery measured in seconds rather than hours — and customers in other parts of the world get faster service because they're served locally. It is one of the strongest continuity guarantees AWS offers for this kind of data.

The trade-off is that it roughly multiplies that table's running cost by the number of Regions, every month, forever. That makes it the right call for the handful of systems where a Region outage is a real revenue or compliance event, and the wrong call as a blanket default. The leadership question is not "are our tables global?" — it's "do we know which systems genuinely require multi-Region survivability, and have we deliberately chosen it only for those?"

At one payments company, the question of multi-Region resilience used to be answered ad hoc — some teams turned on Global Tables because it felt safer, others didn't, and nobody could say which tables actually needed it or what it was costing. The cloud bill carried a growing line for replicated DynamoDB with no clear rationale behind it.

Leadership reframed it. Instead of treating multi-Region as a technical default, they asked engineering to produce a short, named list of business-critical data stores where a Region outage would breach an SLA or stop revenue — and to justify Global Tables only for those. Everything else stayed single-Region with point-in-time recovery and backups. The replicated-table spend went from a creeping, unexplained line to a small, deliberate one tied to specific revenue-critical systems.

That's the right outcome state. The goal was never "make our tables global" or "minimise the DynamoDB bill" — it was "the systems that must survive a Region failure do, and we're not paying a doubling premium on the ones that don't." The continuity posture became something leadership could explain in one sentence.

This category sits at the intersection of business continuity and cost discipline. Under-using Global Tables means a revenue-critical system could be taken offline for hours by a single-Region event — a genuine continuity and possibly contractual risk. Over-using it means paying a permanent doubling premium on tables that never needed it. Both are failures of the same thing: not knowing which systems truly require multi-Region survivability.

The reason it's tracked is that the answer reveals the maturity of the resilience strategy. A short, named, justified list of multi-Region tables means the org has consciously chosen where to spend for continuity. A long or growing list with no rationale — or a critical system conspicuously absent from it — means resilience decisions are being made by default rather than by design, and that pattern usually extends well beyond DynamoDB.