DynamoDB BatchWriteItem: Provided list of item keys contains duplicates

Question

I am trying to use DynamoDB operation BatchWriteItem, wherein I want to insert multiple records into one table.

This table has one partition key and one sort key.

I am using AWS lambda and Go language.

I get the elements to be inserted into a slice.

I am following this procedure.

1. Create PutRequest structure and add AttributeValues for the first record from the list.

2. I am creating WriteRequest from this PutRequest

3. I am adding this WriteRequest to an array of WriteRequests

4. I am creating BatchWriteItemInput which consists of RequestItems, which is basically a map of Tablename and the array of WriteRequests.

After that I am calling BatchWriteItem, which results into an error:

Provided list of item keys contains duplicates.

Any pointers, why this could be happening?

Answer 1

You've provided two or more items with identical partition/sort keys.

Per the BatchWriteItem docs, you cannot perform multiple operations on the same item in the same BatchWriteItem request.

Answer 2

Use batch_writer instead of batch_write_item:

import boto3

dynamodb = boto3.resource("dynamodb", region_name='eu-west-1')
my_table = dynamodb.Table('mirrorfm_yt_tracks')

with my_table.batch_writer(overwrite_by_pkeys=["user_id", "game_id"]) as batch:
    for item in items:
        batch.put_item(
            Item={
                'user_id': item['user_id'],
                'game_id': item['game_id'],
                'score': item['score']
            }
        )

If you don't have a sort key, overwrite_by_pkeys can be None

This is essentially the same answer as @MiguelTrejo (thanks! +1) but simplified