We are designing an application which will use DynamoDB as storage system. I am new to dynamodb, and I came across sparse indexes. Global secondary index is an index that have a partition key and an optional sort key that are different from base table’s primary key. Learn about secondary indexes with AWS DynamoDB. To do this, you take advantage of the fact that table items that do not contain global secondary index attribute(s) are not indexed at all. DynamoDB: Sparse Indexes. Understanding how to use sparse indexes might also help you reconsider which access patterns the user-facing piece of your application actually needs. In this example, let's show how we might use a sparse index for our global secondary index. DynamoDB will backfill the global secondary index based on the existing data in the table. These share the same partition key, but have different attributes for the range key. However, the requirement of using a primary key limits the access patterns of a table. When you write an item, DynamoDB only copies it to the secondary index if the item has elements of the specified key schema for that index. In the last example, we saw how to use the partition key to filter our results. I think they fit for what I need, but I am not completely sure how to implement them. AWS DynamoDB supports two types of indexes: Global Secondary Index (GSI) and Local Secondary Index (LSI). A sparse index is when not every Item contains the attribute you're indexing. Sparse Indexes for Filtering A sparse (secondary) index intentionally excludes certain items from your table to help satisfy a query (aka not merely as a result of PK/SK overloading). Sparse index. We are restricted to a maximum of 5 Local Secondary Indexes (LSIs), that must be created when the table is. As can be seen from the above example, there can be thousands of items in your table but if there is only one item … Items will only appear in an index if they exist in the table on which the index is defined, making queries an index very efficient; DynamoDB Secondary indexes supports two types Global secondary index – an index with a partition key and a sort key that can be different from those on the base table Up to this point, most read operations have used a table's primary key directly, either through the GetItem call or the Query call. are automatically maintained as sparse objects. In this section, we’ll look at a different tool for filtering — the sparse index. Secondary Indexes are sparse meaning if the DynamoDB item doesn’t have the attributes associated with the index, then it won’t appear on the index. Sparse Global Secondary Indexes. 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