SQS vs SNS for Lambda Dead Letter Queues
Development SQS vs SNS for Lambda Dead Letter Queues

Serverless computing and event-driven functions are what it’s all about at the moment. But what happens when the event trigger fires, and your process then encounters an error? How do you recover from this given the event has since passed and may never happen again? This is a common question in AWS when working with their serverless, event-driven Lambda Functions.

Fortunately, AWS lets you define Dead Letter Queues for this very scenario. This option allows you to designate either an SQS queue or SNS topic as a DLQ, meaning that when your Lambda function fails it will push the incoming event message (and some additional context) onto the specified resource. If it’s SNS you can send out alerts or trigger other services (maybe even a retry of the same function - although watch out for infinite loops), or any combination of the above, given its fanout nature. If it’s SQS you can persist the message and process it with another service.

So let’s look at both options in a little more detail.

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Is AWS about to enable Redshift Spectrum with Enhanced VPC Routing?
Development Is AWS about to enable Redshift Spectrum with Enhanced VPC Routing?

AWS is knocking it out of the park at the moment with loads of new services and features coming out every week. Indeed, it can be hard to keep up with the degree of change. But, while working on one of our Redshift clusters today we spotted a potential scoop that would remove a key blocker for one extremely useful service, Redshift Spectrum.

Up until now it’s only been possible to use Spectrum if you don’t have Enhanced VPC Routing enabled on your Redshift cluster. There are so many benefits to using Enhanced VPC Routing (reduced data transfer cost, control, security) that it’s hard to see why anyone wouldn’t be using it, especially if you move data between Redshift and S3 a lot.

But we spotted a new parameter being applied to one of our clusters when we made some maintenance changes to a parameter group. There’s now a parameter named spectrum_enable_enhanced_vpc_routing showing, which hints that Amazon may be about to remove this crucial limitation.

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Impressions of Microsoft’s new-look Power BI
Development Impressions of Microsoft’s new-look Power BI

A couple of months ago, Microsoft’s new-look Power BI Preview rolled out globally. Ditching the Office 365/Sharepoint Online requirement, the new Power BI is a streamlined, simplified version of the product that attempts to lose some of the bloat and give users a focussed, easy-to-use, self-service BI platform.

So has it worked?

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Debugging Errors in SSIS Data Quality Services Cleansing Component
Development Debugging Errors in SSIS Data Quality Services Cleansing Component

As part of Microsoft’s push to include business users in the Business Intelligence space, the addition of Data Quality Services to SQL Server’s feature set opened up the ETL process to the people who, arguably, know the data best. Integration with SSIS was a great move, meaning that this user control extends to automated processes, further closing the gap between data and the business.

However, like most new components, Data Quality Services has some teething problems, and these can be quite hard to find when debugging your SSIS packages. Here’s a quick tip that should help solve some of those tricky to find DQS issues.

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Mapping C# DateTime to SQL Server datetime2 via SSIS
Development Mapping C# DateTime to SQL Server datetime2 via SSIS

With SQL Server 2008, Microsoft introduced the new, improved datetime2 format. This newer time storage format is great, because it takes up less storage space, plus you have control over precision and can define your field to the exact specification required. Database columns defined as datetime2 can be mapped in SSIS by using the DT_DBTIMESTAMP2 type. However, in the scenario where you may have a Script Transformation in your SSIS package, and want to assign a .NET DateTime type to a Data Flow column that is mapped to a datetime2 field, you might encounter a DoesNotFitBufferException.

The reason for this is likely down to your specified field precision, and is easily fixed.

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Building a Raspberry Pi NAS: Enclosure
Development Building a Raspberry Pi NAS: Enclosure

Lately I’ve been experimenting with the Raspberry Pi, the credit-card sized budget computer that took the world by storm back in 2012. I posted the other day about the hardware I’m using to create my own, Raspberry Pi based NAS (Network Attached Storage) slash backup server slash media centre. I mentioned at the end of that article about buying or creating an enclosure to tidy up the Pi-based solution, as well as keep all the components safe and together. It’s not entirely necessary, but if you have a Raspberry Pi, one or two external HDDs, a USB hub and HDMI/Ethernet cables, chances are it’ll be messy and you’ll want to build or buy something to keep everything together all neat and tidy. There are lots of possibilities out there, some you can buy, others you can make. There are lots of cases for the Pi itself, but I needed one to match my particular setup and contain the hard drives, USB hub, and all the related cabling as well.

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Building a Raspberry Pi NAS: Hardware
Development Building a Raspberry Pi NAS: Hardware

The Raspberry Pi has been a huge hit since its launch in 2012, grabbing the attention of hobbyists and professionals alike. The option to buy a fully functional, credit-card sized computer for less than £30 has opened up a slew of possibilities for experimentation and creativity, regardless of budget. I’d been meaning to pick one up for a while, and finally got the push I needed when I started doing some freelance web work and needed a backup system for my client sites and databases. Reading Scott Hanselman’s post regarding the Computer Backup Rule of Three simply drove home the point. I also fancied getting all my media files off my hard drive and into a centralised location on my home network where they could be backed up, easily accessible, and viewed through my TV. Given the option of buying a pre-made NAS box from Amazon, or constructing my own and getting my teeth into that tasty Raspberry Pi, there was no choice to be made!

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picnicerror.net is a personal blog where I post various ideas, thoughts and discoveries through both my day to day work in marketing technology and general hobbies and interests.

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