DynamoDB

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What is Amazon DynamoDB?

create database tables that can store and retrieve any amount of data and serve any level of request traffic
- can scale up or scale down the table's throughput capacity without downtime or performance degradation
provides on-demand backup capability
- create on-demand backups and enable point-in-time recovery for your database
- with point-in-time recovery, you can restore a table to any point in time during the last 35 days
it allows you to delete expired items from tables automatically to help reduce storage usage and the cost of storing data that is no longer relevant

High Availability and Durability

automatically spreads the data and traffic for your tables over a sufficient number of servers to handle your throughput and storage requirements
maintains consistent and fast performance
- stored on SSDs and automatically replicated across multiple Availability Zones in an AWS region
- can use global tables to keep DynamoDB tables in sync across AWS regions

Amazon DynamoDB: How it Works

Cheat Sheet for DynamoDB

Basic Actions

Create a table

Default

aws dynamodb create-table \
        --table-name Music \
        --attribute-definitions \
            AttributeName=Artist,AttributeType=S \
            AttributeName=SongTitle,AttributeType=S \
        --key-schema \
            AttributeName=Artist,KeyType=HASH \
            AttributeName=SongTitle,KeyType=RANGE \
        --provisioned-throughput \
            ReadCapacityUnits=10,WriteCapacityUnits=5

Windows

aws dynamodb put-item --table-name Music --item "{\"Artist\": {\"S\": \"No One You Know
\"}, \"SongTitle\": {\"S\": \"Call Me Today\"}, \"AlbumTitle\": {\"S\": \"Somewhat
 Famous\"}, \"Awards\": {\"N\": \"1\"}}"

Read item to a table

aws dynamodb put-item \ --table-name Music \ --item file://item.json

Write item to a table

aws dynamodb get-item \ --table-name Music \ --item file://item.json

Delete item from a table

aws dynamodb delete-item --table-name Music --key file://key.json

Query a table

aws dynamodb query --table-name Music
--key-condition-expression "ArtistName=:Artist and SongName=:Songtitle"

Delete a table

aws dynamodb delete-table --table-name Music

List table names

aws dynamodb list-tables

Naming Rules

All names must be encoded using UTF-8 and are case sensitive.
Table names and index names must be between 3 and 255 characters long, and can contain only the following characters:
- a-z
- A-Z
- 0-9
- _(underscore)
- -(dash)
- .(dot)
Attribute names must be at least one character long, and less than 64 KB in size.

Service Quota Basics

Read and write units

Read capacity unit (RCU)—One strongly consistent read per second, or tow eventually consistent reads per second, for items up to 4 KB in size.
Write capacity unit (WCU)—One write per second, for items up to 1 KB in size.

Table limits

Table size—no practical limit on table size (i.e., no constraints on number of items or number of bytes)
Number of tables—initial quota of 2,500 tables per AWS Region
Page size limit for a query and scan—1 MB per page, per query or scan
- if a query or scan returns more than 1 MB of data, DynamoDB returns the initial matching items and a LastEvaluatedKey property that you can use in a new request to read the next page

Last modified: 10 March 2024