In this article we are going to set up dynamodb on our local development environment. A short description of a couple of easy-to-use management tools is included.
DynamoDB Start by downloading the DynamoDB development version. Uncompress the file and create a launch script with the following contents:
#!/bin/sh java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar -sharedDb -port 8000 The script will launch dynamo on port 8000 and will create a file called shared-local-instance.
The BatchWriteItem operation allows us to work with groups of up to 25 items per request. Additionally, we can put and delete items to one or multiple tables. Amazon DynamoDB’s page says:
A single call to BatchWriteItem can write up to 16 MB of data, which can comprise as many as 25 put or delete requests. Individual items to be written can be as large as 400 KB.
In this article we are going to go through the process of putting and deleting items to a table that looks like this:
Should I use a map or a list? A simple rule:
If you need to update or remove an item, lists only allow you to do it by index. While maps let you do it by key. Their simplified representation goes like this:
{ "someMap": { "key1": "value1", "key2": "value2", }, "someList": ["value1", "value2"] } Inserting and updating to a map The following example adds or updates an instance of “SomeItem” as a json string into a map field called someMapField.
