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DynamoDB
Development with AWS ServicesFully managed, serverless NoSQL key-value and document database.
Keys & indexes
- ▸Partition key alone, or partition key + sort key (composite key).
- ▸LSI: alternate sort key, same partition key, must be created at table creation, shares table throughput.
- ▸GSI: alternate partition + sort key, own throughput, can be created/deleted anytime.
Capacity modes
- ▸Provisioned: set RCU/WCU ahead of time, use Auto Scaling to adjust; cheaper for predictable workloads.
- ▸On-demand: pay-per-request, scales instantly; better for unpredictable/spiky traffic.
Consistency & performance
- ▸Eventually consistent reads (default, cheaper) vs strongly consistent reads (RequestConsistency, 2x cost).
- ▸DAX (DynamoDB Accelerator): in-memory cache, microsecond reads, reduces read load — for read-heavy workloads.
- ▸Hot partitions cause throttling — fix with better key cardinality/distribution or write sharding.
Advanced features
- ▸DynamoDB Streams: time-ordered change log of item-level modifications, consumed by Lambda for triggers/replication.
- ▸Conditional writes (e.g. attribute_not_exists) enforce atomic checks without a separate read.
- ▸TransactWriteItems / TransactGetItems: all-or-nothing multi-item ACID transactions across tables.
- ▸TTL: automatically expire/delete items based on a timestamp attribute, at no extra write cost.