Question 1

What does DynamoDB consulting cover?

Accepted Answer

Partition key + sort key audit (hot-partition prevention, query-pattern alignment, GSI design), Global Tables multi-region topology, RCU/WCU vs on-demand billing-mode selection, DAX caching strategy, Streams + Lambda pipeline design (real-time analytics, replication, audit logging), DynamoDB → MongoDB Atlas migration scoping, Reserved Capacity opportunity analysis. Written architecture documents with rationale, not Slack-thread guesses.

Question 2

Partition key is wrong — can we fix it without rewriting everything?

Accepted Answer

Sometimes. Options ranked from cheapest to most expensive: (1) Add GSI with the right partition key for the access pattern, keeping the original PK — only works if storage cost of GSI is acceptable, (2) Add a write-shard (random suffix on PK) to spread heat — works if reads can scatter-gather, (3) Migrate to a new table via DMS or Glue with the corrected partition key — full rewrite but reversible. We audit the workload and recommend the right intervention before committing to a full migration.

Question 3

On-demand vs provisioned + Reserved — which is cheaper for us?

Accepted Answer

Workload-dependent. We model: peak/average RCU+WCU ratio, hours-of-active-use per day, growth trajectory. Typical findings: predictable steady-state production with peak/avg ratio under 3:1 → provisioned + Reserved Capacity wins (50-80% discount). Variable / unpredictable / dev workloads → on-demand wins. Most teams switching from on-demand to provisioned + Reserved save 40-60% with no application changes. We do the modelling before recommending.

Question 4

Global Tables — do I really need it?

Accepted Answer

Often no. Global Tables doubles or triples write cost (writes replicate to every region) + adds cross-region transfer cost. Use cases that genuinely need it: regulatory data-residency requiring in-region writes, global apps where read latency from a single region exceeds budget, RTO requirement for full-region failure that single-region + Cross-Region Replication can't meet. For most workloads, single-region + Multi-AZ failover + periodic DR-region snapshot restore is sufficient at a fraction of the cost.

Question 5

DAX vs ElastiCache for caching?

Accepted Answer

DAX: managed, DynamoDB-native, microsecond reads, item-level caching with automatic invalidation on writes — but limited to DynamoDB workloads, no general-purpose caching. ElastiCache (Redis or Memcached): general-purpose, ms-level reads, requires application-tier cache code + invalidation strategy. Pick DAX when: cache-able DynamoDB read traffic dominates and you want zero app-tier cache code. Pick ElastiCache when: cache shared across multiple data sources, complex caching patterns (sorted sets, pub/sub), or you already run ElastiCache.

Question 6

DynamoDB → MongoDB Atlas migration — when does this make sense?

Accepted Answer

Triggers: (a) multi-cloud strategy needs AWS-only escape, (b) workload outgrew key-value access patterns and needs aggregation pipeline / $lookup, (c) Atlas Vector Search for RAG workloads, (d) team finds MongoDB ergonomics better than DynamoDB constraints. Migration: AWS DMS or Glue export to S3 → Atlas import. The application-tier rewrite (PutItem → insertOne, Query → find, GSI patterns → secondary indexes) is the dominant cost. See MongoDB vs DynamoDB.

Question 7

Does consulting include migration execution?

Accepted Answer

No — execution lives on dedicated engagements. Consulting is the decision phase: audit partition keys, design Global Tables topology, model billing economics, plan DAX vs ElastiCache, scope migration paths. Execution covers DynamoDB → MongoDB Atlas cutover, RCU/WCU billing mode change with auto-scaling, Streams + Lambda pipeline implementation. The split keeps consulting deliverables crisp.

Amazon DynamoDB Consulting

What our DynamoDB consulting covers

DynamoDB consulting — common questions

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