Questions tagged with Amazon DynamoDB Accelerator (DAX)

Hello team, So recently, I was trying to enable DAX instead of using the normal DynamoDB client. And I found this issue. When I'm issuing a Update with this: ``` "Update": { "Key": { "id": { "S": "de26b619-d3e1-4de9-a338-12f95780538f" } }, "ConditionExpression": "#a0 = :v0 AND #a1 = :v1", "ExpressionAttributeNames": { "#a0": "tenantId", "#a1": "_version", "#a2": "updatedAt", "#a3": "_version", "#a4": "totalAmountOutstanding", "#a5": "items" }, "ExpressionAttributeValues": { ":v0": { "S": "HelmTest" }, ":v1": { "N": "1" }, ":v2": { "N": "1650900411690" }, ":v3": { "N": "2" }, ... ``` So basically, I'm using the field `_version` to implement optimistic locking. When using DAX to run this update, I got the error: ``` { "errorType": "Error", "errorMessage": "ValidationException: Two document paths overlap with each other; must remove or rewrite one of these paths _version", "code": "ValidationException", "time": 1650900411978, "retryable": false, "requestId": null, "statusCode": -1, "_tubeInvalid": false, "waitForRecoveryBeforeRetrying": false, "stack": [ "Error: ValidationException: Two document paths overlap with each other; must remove or rewrite one of these paths _version", " at Function.newValidationException (/node_modules/amazon-dax-client/src/RequestValidator.js:383:12)", " at /node_modules/amazon-dax-client/src/RequestValidator.js:84:34", " at Array.forEach (<anonymous>)", " at Function.validateExprAttrNames (/node_modules/amazon-dax-client/src/RequestValidator.js:78:30)", " at Function.validateExpression (/node_modules/amazon-dax-client/src/RequestValidator.js:217:42)", " at /node_modules/amazon-dax-client/src/BaseOperations.js:603:26", " at processTicksAndRejections (internal/process/task_queues.js:95:5)", " at p2 (/node_modules/dynamoose/lib/aws/ddb/internal.ts:30:17)", " at /node_modules/dynamoose/lib/Transaction.ts:99:23", ``` The library complains that it won't allow me to use `_version` many times. I looked into the source code, and this is confirmed: ``` let attrs = new Set(); Object.keys(attrNames).forEach((k) => { let v = attrNames[k]; if(k == null) { throw new AmazonClientException('ExpressionAttributeNames contains invalid key: null'); } if(attrs.has(v)) { throw RequestValidator.newValidationException('Two document paths overlap with each other; must remove or rewrite one of these paths ' + v); } attrs.add(v); ``` I believe this is a bug in the library, as this is a normal use case and it should be allowed. For now, I've turned off the DAX and gone back to the normal DynamoDB client, where things are working.

If we use only PartiQL for Dynamodb calls, do the calls get automatically routed via DAX because we are using DAX cache also in front of some of our tables. Basically how to use PartiQL along with DAX Thanks

I am seeing this error intermittently "Timeout waiting for an available tube" from our DAX cluster. Its three-node cluster. What could be the issue.

While connecting to encrypted Amazon DAX Cluster using DAX Java SDK we are getting following error ``` failed to configure cluster endpoints from hosts: [<DAX-Cluster-Endpoint>:9111] ``` We are using following dax sdk maven dependency ``` `<dependencies> <dependency> <groupId>com.amazonaws</groupId> <artifactId>amazon-dax-client</artifactId> <version>1.0.230341.0</version> </dependency> </dependencies>` ``` Code Snippet ``` DynamoDB getDaxClient(String daxEndpoint) { AmazonDaxClientBuilder daxClientBuilder = AmazonDaxClientBuilder.standard(); daxClientBuilder.withRegion(region).withEndpointConfiguration(daxEndpoint); AmazonDynamoDB client = daxClientBuilder.build(); return new DynamoDB(client); } ``` DAX Cluster is in ap-south-1 region. However, I am able to connect DAX from local machine and ec2 instances when running nc command ``` nc -z <DAX-Cluster-Endpoint> 9111 Connection to<DAX-Cluster-Endpoint> port 9111 [tcp/*] succeeded! ``` Note : 9091 port is open for our VPC in security group associated with the DAX cluster

Hi, I am using the DAX Python client as below and I eventually use batch_write_item as below. ``` session = botocore.session.get_session() dax_hook = amazondax.AmazonDaxClient(session, region_name="us-east-1", endpoints=[endpoint]) . . . with concurrent.futures.ThreadPoolExecutor( max_workers=MAX_WORKERS ) as executor: for items_data_batch in items_data: executor.submit(write_batch, dax_hook, items_data_batch, ddb_table_name) ``` The write_batch function essentially tries to write to the cache (and eventually table) via dax_hook.batch_write_item(RequestItems={table_name: batch}). The issue I am facing is this succeeds most of the time but sometimes I get an exception as below. If I retry the batch, with high probability this works (out of 30M keys, 175 fail after this retry; most succeed on the first try). I am not sure, how do we interpret this Exception? I pulled some of the batches that failed and reran and this also worked (on first try), so I am thinking the ValidationException does not make sense (I have a few ideas about what might be the problem but I am not sure). Is this a possible bug in the Exception logic, and another Exception should be thrown? The Exception I am getting looks like this: ERROR - An error occurred (ValidationException) when calling the operation: Unknown parameter in RequestItems.some-table\[0\].PutRequest: "attr_names", must be one of: Item

Is it possible to read from DAX with benefit of SDK V3 for JS usage? I would like to configure reading from specified DAX endpoint but I can't find any details how to do it. I only found following solution for SDK V2: ``` var dax = new AmazonDaxClient({endpoints: ["DaxClusterEndpoint"], region: region}) daxClient = new AWS.DynamoDB.DocumentClient({service: dax }); ``` I can't use DocumentClient from SDK V3 to initialize it with AmazonDaxClient from SDK V3 and I also can't find any option to use "@aws-sdk/client-dax" with specified endpoint and then add it to DynamoDBDocumentClient from V3. Any suggestions if it's even possible? With usage of AmazonDaxClient my lambda is getting big in size.

Is there a way to use a service integration from API Gateway (REST) for DAX? I know we can use a service integration for DynamoDB, but DAX is supposed to be a transparent replacement with respect to the API. Seems like a big waste to reintroduce a Lambda in between just because I want to add caching, and this goes against the 'Servicefull' best practice.

Hi all, I have a piece of code which is getting data for array of params after all the Promise settled i am returning the response.I am using DAX service. On first read i am getting the response but when i am reading for 2nd Time.I am not getting any response.does the implemented code works with DAX? ``` let queryArray: any = []; let response: any[] = []; const promiseRes: any = await Promise.allSettled( params.map(async (param) => { let data: any = await this.client.query(param).promise(); queryArray = [...queryArray, ...data.Items]; while (typeof data.LastEvaluatedKey != 'undefined') { param['ExclusiveStartKey'] = data.LastEvaluatedKey; data = await this.client.query(param).promise(); queryArray = [...queryArray, ...data.Items]; } return queryArray; }) ); ```