Data Stores Flashcards
What is a data store?
A data store is a repository for persistently storing and managing collections of data which include not just repositories like databases, but also simpler store types such as simple files, emails etc.
What are important features of a data store?
- Data persistence
- IOPS and Throughput
- Consistency
What is persistent data storage?
Data that is durable and remains after reboots, restarts and power cycles
What are the types of data persistence?
- Persistent
- Transient
- Ephemeral
What core AWS services use persistent data storage?
- Glacier
2. RDS
What is transient data storage?
Data that is stored temporarily and passed along to another process or persistent store
What core AWS services use transient data storage?
- SQS
2. SNS
What is ephemeral data storage?
Data that is lost when instances or services are stopped
What core AWS services use ephemeral data storage?
- Instance store
2. memcached
What is IOPS?
Input/Output operations per second which measures how fast we can read and write to a device
What is throughput?
How much data we can transfer at any given time
What is data consistency?
A matter of keeping things in order like a set of ground rules so that data behaves in the same way
What are the consistency models?
- ACID
2. BASE
What is the ACID model?
Atomic – transactions are “all or nothing” (no partial transactions)
Consistent – transactions must be valid (not corrupted)
Isolated – transactions can’t interfere with one another
Durable – completed transaction must stick around
What is the BASE model?
Basic Availability – values availability even if stale
Soft-state – might not be instantly consistent across stores
Eventual consistency – will achieve consistency at some point
