How to set DynamoDB Read Consistency

Question

Hi
How do I configure strongly consistent read in DynamoDB? I can't find where to set strongly consistent and eventually consistent reads

Thank you

Accepted Answer

Hi, look at https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadConsistency.html

It provides following details:

***Strongly Consistent Reads**
Read operations such as GetItem, Query, and Scan provide an optional ConsistentRead parameter. If you set ConsistentRead to true, DynamoDB returns a response with the most up-to-date data, reflecting the updates from all prior write operations that were successful. Strongly consistent reads are only supported on tables and local secondary indexes. Strongly consistent reads from a global secondary index or a DynamoDB stream are not supported.
*

Answer

At the request level, you have the flexibility to specify whether you want to use strong consistency or eventual consistency for different methods. Strongly consistent reads are enabled by setting a parameter value, indicating to DynamoDB that the read operation should be served from the leader node, ensuring immediate and up-to-date data. On the other hand, eventual consistency allows the read to be served from any of the three nodes, which may have slightly delayed updates. This parameter value allows you to choose the desired consistency level for each specific method you call in DynamoDB.

An example using CLI:

Consistent Read

aws dynamodb scan \
--table-name Mytable \
--consistent-read

Eventually Consistent Read

aws dynamodb scan \
--table-name Mytable \
--no-consistent-read

In the SDK's, it uses the Boolean parameter ConsistentRead which you can set to True or False.

More info here in the docs.

An example using CLI:

**Consistent Read**
```
aws dynamodb scan \
--table-name Mytable \
--consistent-read
```

**Eventually Consistent Read**
```
aws dynamodb scan \
--table-name Mytable \
--no-consistent-read
```

In the SDK's, it uses the Boolean parameter [`ConsistentRead`](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_Scan.html#DDB-Scan-request-ConsistentRead) which you can set to `True` or `False`.

More info [here](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadConsistency.html) in the docs.

How to set DynamoDB Read Consistency

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