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Local Secondary Index In Dynamodb

In this article, we will discuss the local secondary index in DynamoDB.

Purpose

In DynamoDB, the data is retrieved quickly using the primary key (partition key + sort key). But if you want to use other columns (other than the primary key columns) to retrieve the data quickly, then we create the local secondary index.

How To Create A Local Secondary Index?

Please note that you can only create the local secondary index at the time of table creation. When you create the table, select Table settings as Customize settings.

Picture showing the Table settings while creating the dynamodb table

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Scroll down to the Secondary indexes and click on the Create local index button.

Picture showing the Secondary indexes section for creating the index

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A popup window will appear, where you can enter the Sort key, Data type, and the Index name.

Picture showing the screen for creating the new secondary index

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Click on the Create index button to create the index. The popup window is closed and the secondary index is added in the Secondary indexes section.

Picture showing the secondary index created for dynamodb table

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How Do You Use Index For Query Or Scan?

Once the table is created, click on the table and click on the Explore table items button.

Picture showing the Explore table items button in the table detail screen

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In the Scan or query items section, select the Select a table or index dropdown.

Picture showing the screen for querying or scanning table

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Scan Vs Query

Query is used when you need to retrieve specific items based on key conditions, and you want to leverage the efficiency of primary key lookups or secondary indexes.

A scan is used when you need to read all items in a table or when you need to filter items based on non-key attributes. However, be cautious with Scan on large tables, as it can be resource-intensive.

Posted By -	Karan Gupta

Posted On -	Thursday, November 2, 2023

Updated On -	Friday, November 24, 2023

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