Pagination is a crucial concept in DynamoDB for efficiently retrieving large sets of records. By default, DynamoDB has a querying limit of 1 MB, which means it only returns data within that size. However, by implementing pagination, you can break down the records into smaller, manageable chunks, enabling you to retrieve data iteratively and avoid exceeding the limit.
1. Query Page Size:
Query page size refers to breaking the records in DynamoDB into smaller chunks. By specifying the query page size, you determine the number of records to be queried in each iteration. However, it's important to note that the 1 MB limit still applies to the query page size. For instance, if the page size is set to 3, but the combined size of the first two records exceeds 1 MB, DynamoDB will ignore the third record. Carefully assigning the query page size is crucial for efficient pagination.
2. Exclusive Start Key:
The exclusive start key serves as a pointer indicating the record from which the data querying should start. By default, the exclusive start key is set to null, which means pagination begins with the first record in the table. As you retrieve each set of records, you can use the last evaluated key from the previous query as the exclusive start key for the next iteration, enabling sequential data retrieval.
3. Last Evaluated Key:
The last evaluated key is the key of the last record that DynamoDB reads in a pagination operation. To continue pagination, you need to provide the last evaluated key as the exclusive start key in the subsequent query. When DynamoDB returns a null value for the last evaluated key, it indicates that there are no more records remaining, and pagination is complete.
Implementing pagination in DynamoDB allows you to efficiently retrieve large sets of records by breaking them into smaller, manageable chunks. By carefully assigning the query page size and utilizing the exclusive start key and last evaluated key, you can retrieve data sequentially and overcome the 1 MB querying limit. Pagination is a powerful technique for optimizing data retrieval in DynamoDB and ensuring efficient handling of large datasets.