Databases - DynamoDB Flashcards
What is DynamoDB
fast and flexible NoSQL database service for all apps that need consistent, single-digit millisecond latency at any scale.
Is DynamoDB fully managed?
Yes
What models does DynamoDB support?
Document, key-value
Uses for DynamoDB
mobile, web, gaming, ad-tech, IoT
Where is data in DynamoDB stored?
SSD Storage
Where is DynamoDB spread?
across 3 geographically distinct data centers (not AZs)
Default consistency model for DynamoDB
Eventual Consistent Reads. Strongly consistent reads is the other
Eventual Consistent Reads
Consistency across all copies of data is usually reached within 1 second. repeating a read after a short time should return the updated data (best read performance)
Strongly Consistent Reads
returns the result that reflects all writes that received a successful response prior to the read. May not be available if there is an outage or delay. Not supported across AWS regions.
If low latency is important
pick Eventual consistent reads. Otherwise, pick strongly consistent reads
DynamoDB pricing
Provisioned throughput capacity, reading, writing and storage of data in tables
How expensive is DynamoDB?
Expensive for writes, cheap for reads
Use case for DynamoDB
If DB is read-heavy, scalabilty and good performance are important, SQL is not necessary
default read and write capacity units when creating a DynamoDB table
5, 5
can you purchase reserved capacity?
Yes, 1 or 3-year terms
Item
Row
Important metrics to know
Read capacity Units, Write capacity units (both provisioned/consumed)
What are some key security features?
Encryption at rest using KMS, AES-256 encryption; authentication and authorization
What are tables?
a collection of items that are schema less with a limit of 256 tables per region
What are items?
a collection of attributes that used primary keys to uniquely identify each item in a table and secondary indexes to provide more querying flexibility.
What are attributes?
a fundamental data element
What is a primary key?
uniquely ids each item in a table and no two items can have the same key
What the different types of primary keys?
A simple partition key with on attribute and a composite partition/sort key with two attributes
What are secondary indexes?
Query data in a table using an alternate key, in addition to queries of primary
