DynamoDB Flashcards
What is provisioned throughput in DynamoDB?
Your read / write capacity.
Is data in DynamoDB strong consistent, or eventually consistent?
Eventually consistent. But very fast.
DynamoDB automatically copies your data to … availability zones.
3
DynamoDB can not be as complex as SQL queries. This is by design. Why?
To push logic away from the database layer and to the computer layer
Can dates be stored in DynamoDB straight up?
Nope. Must be converted to a time stamp
What are the maximum amount of indexes allowed on a DynamoDB table?
10
What’s max item size in DynamoDB
400kb
In DynamoDB what is a composite key?
When you specify a primary key and a sort key
True or false. In Dynamo database the only way to look up data is by primary key?
True
What are the default read/writes in DynamoDB
5
Does DynamoDB allow for bursting above capacity?
Yes but it’s very limited, and no details are specified by AWS
True or false. AWS use DynamoDB burst capacity for maintenance
True
In DynamoDB what is an RCU
Read capacity unit
In DynamoDB what is a WCU
Write capacity unit
The size limit of one DynamoDB RCU is…
4kb
You need to retrieve an item from DynamoDB which is 16kb in size. How many RCUs will this use?
4
1 RCU = 4kb
16kb/4kb =4
Are RCU requests strongly or eventually consistent?
By default, strongly. But they can be set to eventually.
What’s the benefit of an eventually consistent RCU
They cost half compared to a strongly consistent RCU
Want to query DynamoDB. Your two options are…
Query
Scan
Want to search a whole table across all partion keys? What to use?
A scan
Want to search a specific table for a single portion key? What to use?
A query
Can DynamoDB scans be strongly consistent?
No. Only eventually.
Can DynamoDB scans be ran in parallel?
Yes
Can DynamoDB scans be ordered?
No
Generally speaking. Will a query or a scan use more RCU’s
Scan
Can a DynamoDB query be ordered?
Yes. By sort key.
Are DynamoDB queries strongly or eventually consisent?
Either. strongly by default
What is the size limit of one WCU in DynamoDB
1kb
In DynamoDB must you provision throughput for each secondary index?
Yes
In DynamoDB database what is a GSI?
Global secondary index
What is the GSI limit per table in DynamoDB
5
In DynamoDB what is an LSI
Local secondary index
What is the LSI limit per DynamoDB table?
5
True or false. LSIs share throughput of the existing table in DynamoDB
True
When creating a primary key in an index. You can choose what …… you project into the index.
Attributes
Is partioning in DynamoDB automatic?
Yes
What triggers partioning in DynamoDB
A table getting to 10gb in size. Or. High throughput.
You want to know how many partitions your DynamoDB table has. How do you do this?
Contact AWS
Can DynamoDB partitions be removed or reduced after creation?
No
In DynamoDB partion keys are also sometimes known as
Hash keys
Describe what happens when a partition is created in DynamoDB
Two new partitions are created. Data is copied to these new partions and the original partition is deleted.
Do dynamo database read and writes slow as the table increases in size?
No
