DynamoDB GSI Boolean Data Type Limitations: What You Need to Know
Tags: gsi, serverless, aws, nosql
Published: 2023-02-26 19:18:31

DynamoDB, a NoSQL database provided by Amazon Web Services (AWS), is a highly scalable and fully managed database that provides fast and predictable performance with seamless scalability. However, there are certain limitations in DynamoDB that developers should be aware of to ensure optimal performance and scalability.


![Architecture and components of DynamoDB](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/q39mo8zphj8kw9u2f9h1.PNG)

One such limitation is that DynamoDB does not permit Boolean data types as an index key attribute. This is due to the fact that Boolean data types only have two possible values (true or false), which results in poor distribution of items across partition keys. This, in turn, can negatively impact query efficiency.

Efficient querying and searching of data is critical in DynamoDB, as indexes are utilized for this purpose. However, the Boolean data type does not provide a sufficiently large number of unique values to support efficient indexing. As a result, it is recommended to use a different data type, such as a string or number, as the index key attribute.

To better understand this limitation, it's important to know that every Global Secondary Index (GSI) in DynamoDB must have a partition key and a sort key. This is because GSIs are designed to support fast and efficient querying and searching the data based on specific attributes. The partition key distributes data evenly across multiple partitions, while the sort key further orders the data within each partition.

```
+---------------------------+
|  DynamoDB Table           |
+---------------------------+
|  Partition Key            |
+---------------------------+
|  Sort Key                 |
+---------------------------+
|  Global Secondary Index   |
+---------------------------+
|  Data Items               |
+---------------------------+

```

By requiring every GSI to have a partition key and sort key, DynamoDB ensures that data is well-distributed across partitions and can be efficiently queried and searched based on specific attributes. This is critical to ensuring good performance and scalability of the database.

To work around the limitation of Boolean data types in DynamoDB, developers can use other data types, such as a string or number, as the index key attribute. This will ensure that the values are well-distributed and can be efficiently queried and searched.

It's also important to note that DynamoDB does not permit creating a table if an index is meant to always be a GSI without a hash key or range key. This is because it would result in poor distribution of data and inefficient querying and searching of data.

In conclusion, DynamoDB is a powerful NoSQL database that can provide fast and predictable performance with seamless scalability. However, developers must be aware of certain limitations, such as the inability to use Boolean data types as an index key attribute, in order to ensure optimal performance and scalability. By using a different data type and ensuring that every GSI has a partition key and sort key, developers can ensure that their data is well-distributed and can be efficiently queried and searched based on specific attributes.