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Add DynamoDB time series data gotcha

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Uli Stroetz 2016-10-12 18:40:03 -04:00 • committed by ustroetz
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@ -625,7 +625,7 @@ S3
- S3 has a [static website hosting option](http://docs.aws.amazon.com/AmazonS3/latest/dev/WebsiteHosting.html) that is simply a setting that enables configurable HTTP index and error pages and [HTTP redirect support](http://docs.aws.amazon.com/AmazonS3/latest/dev/how-to-page-redirect.html) to [public content](http://docs.aws.amazon.com/AmazonS3/latest/dev/WebsiteAccessPermissionsReqd.html) in S3. It’s a simple way to host static assets or a fully static website. - S3 has a [static website hosting option](http://docs.aws.amazon.com/AmazonS3/latest/dev/WebsiteHosting.html) that is simply a setting that enables configurable HTTP index and error pages and [HTTP redirect support](http://docs.aws.amazon.com/AmazonS3/latest/dev/how-to-page-redirect.html) to [public content](http://docs.aws.amazon.com/AmazonS3/latest/dev/WebsiteAccessPermissionsReqd.html) in S3. It’s a simple way to host static assets or a fully static website.
- Consider using CloudFront in front of most or all assets: - Consider using CloudFront in front of most or all assets:
- Like any CDN, CloudFront improves performance significantly. - Like any CDN, CloudFront improves performance significantly.
- 🔸SSL is only supported on the built-in amazonaws.com domain for S3. S3 supports serving these sites through a [custom domain](http://docs.aws.amazon.com/AmazonS3/latest/dev/website-hosting-custom-domain-walkthrough.html), but [not over SSL on a custom domain](http://stackoverflow.com/questions/11201316/how-to-configure-ssl-for-amazon-s3-bucket). However, [CloudFront allows you to serve a custom domain over https](http://docs.aws.amazon.com/acm/latest/userguide/gs-cf.html). Amazon provides free SNI SSL/TLS certificates via Amazon Certificate Manager. [SNI does not work on very outdated browsers/operating systems](https://en.wikipedia.org/wiki/Server_Name_Indication#Support). Alternatively, you can provide your own certificate to use on CloudFront to support all browsers/operating systems. - 🔸SSL is only supported on the built-in amazonaws.com domain for S3. S3 supports serving these sites through a [custom domain](http://docs.aws.amazon.com/AmazonS3/latest/dev/website-hosting-custom-domain-walkthrough.html), but [not over SSL on a custom domain](http://stackoverflow.com/questions/11201316/how-to-configure-ssl-for-amazon-s3-bucket). However, [CloudFront allows you to serve a custom domain over https](http://docs.aws.amazon.com/acm/latest/userguide/gs-cf.html). Amazon provides free SNI SSL/TLS certificates via Amazon Certificate Manager. [SNI does not work on very outdated browsers/operating systems](https://en.wikipedia.org/wiki/Server_Name_Indication#Support). Alternatively, you can provide your own certificate to use on CloudFront to support all browsers/operating systems.
- 🔸If you are including resources across domains, such as fonts inside CSS files, you may need to [configure CORS](https://docs.aws.amazon.com/AmazonS3/latest/dev/cors.html) for the bucket serving those resources. - 🔸If you are including resources across domains, such as fonts inside CSS files, you may need to [configure CORS](https://docs.aws.amazon.com/AmazonS3/latest/dev/cors.html) for the bucket serving those resources.
- Since pretty much everything is moving to SSL nowadays, and you likely want control over the domain, you probably want to set up CloudFront with your own certificate in front of S3 (and to ignore the [AWS example on this](http://docs.aws.amazon.com/AmazonS3/latest/dev/website-hosting-custom-domain-walkthrough.html) as it is non-SSL only). - Since pretty much everything is moving to SSL nowadays, and you likely want control over the domain, you probably want to set up CloudFront with your own certificate in front of S3 (and to ignore the [AWS example on this](http://docs.aws.amazon.com/AmazonS3/latest/dev/website-hosting-custom-domain-walkthrough.html) as it is non-SSL only).
- That said, if you do, you’ll need to think through invalidation or updates on CloudFront. You may wish to [include versions or hashes in filenames](https://abhishek-tiwari.com/post/CloudFront-design-patterns-and-best-practices) so invalidation is not necessary. - That said, if you do, you’ll need to think through invalidation or updates on CloudFront. You may wish to [include versions or hashes in filenames](https://abhishek-tiwari.com/post/CloudFront-design-patterns-and-best-practices) so invalidation is not necessary.
@ -665,7 +665,7 @@ S3
- 🔸After uploading, any change that you make to the object causes a full rewrite of the object, so avoid appending-like behavior with regular files. - 🔸After uploading, any change that you make to the object causes a full rewrite of the object, so avoid appending-like behavior with regular files.
- 🔸Eventual data consistency, as discussed above, can be surprising sometimes. If S3 suffers from internal replication issues, an object may be visible from a subset of the machines, depending on which S3 endpoint they hit. Those usually resolve within seconds; however, we’ve seen isolated cases when the issue lingered for 20-30 hours. - 🔸Eventual data consistency, as discussed above, can be surprising sometimes. If S3 suffers from internal replication issues, an object may be visible from a subset of the machines, depending on which S3 endpoint they hit. Those usually resolve within seconds; however, we’ve seen isolated cases when the issue lingered for 20-30 hours.
- 🔸**MD5s and multi-part uploads:** In S3, the [ETag header in S3](http://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommonResponseHeaders.html) is a hash on the object. And in many cases, it is the MD5 hash. However, this [is not the case in general](http://stackoverflow.com/questions/12186993/what-is-the-algorithm-to-compute-the-amazon-s3-etag-for-a-file-larger-than-5gb) when you use multi-part uploads. One workaround is to compute MD5s yourself and put them in a custom header (such as is done by [s4cmd](https://github.com/bloomreach/s4cmd)). - 🔸**MD5s and multi-part uploads:** In S3, the [ETag header in S3](http://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommonResponseHeaders.html) is a hash on the object. And in many cases, it is the MD5 hash. However, this [is not the case in general](http://stackoverflow.com/questions/12186993/what-is-the-algorithm-to-compute-the-amazon-s3-etag-for-a-file-larger-than-5gb) when you use multi-part uploads. One workaround is to compute MD5s yourself and put them in a custom header (such as is done by [s4cmd](https://github.com/bloomreach/s4cmd)).
- 🔸**US Standard region:** Most S3 endpoints match the region they’re in, with the exception of the us-east-1 region, which is called 'us-standard' in S3 terminology. This region is also the only region that is replicated across coasts. As a result, latency varies more in this region than in others. You can minimize latency from us-east-1 by using *[s3-external-1.amazonaws.com](http://s3-external-1.amazonaws.com/)*. - 🔸**US Standard region:** Most S3 endpoints match the region they’re in, with the exception of the us-east-1 region, which is called 'us-standard' in S3 terminology. This region is also the only region that is replicated across coasts. As a result, latency varies more in this region than in others. You can minimize latency from us-east-1 by using *[s3-external-1.amazonaws.com](http://s3-external-1.amazonaws.com/)*.
### Storage Durability, Availability, and Price ### Storage Durability, Availability, and Price
@ -985,6 +985,7 @@ DynamoDB
- 🔸 DynamoDB doesn’t provide an easy way to bulk-load data (it is possible through [Data Pipeline](http://docs.aws.amazon.com/datapipeline/latest/DeveloperGuide/dp-importexport-ddb-part1.html), and this has some [unfortunate consequences](http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GuidelinesForTables.html#GuidelinesForTables.AvoidExcessivePTIncreases). Since you need to use the regular service APIs to update existing or create new rows, it is common to temporarily turn up a destination table’s write throughput to speed import. But when the table’s write capacity is increased, DynamoDB may do an irreversible split of the partitions underlying the table, spreading the total table capacity evenly across the new generation of tables. Later, if the capacity is reduced, the capacity for each partition is also reduced but the total number of partitions is not, leaving less capacity for each partition. This leaves the table in a state where it much easier for hotspots to overwhelm individual partitions. - 🔸 DynamoDB doesn’t provide an easy way to bulk-load data (it is possible through [Data Pipeline](http://docs.aws.amazon.com/datapipeline/latest/DeveloperGuide/dp-importexport-ddb-part1.html), and this has some [unfortunate consequences](http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GuidelinesForTables.html#GuidelinesForTables.AvoidExcessivePTIncreases). Since you need to use the regular service APIs to update existing or create new rows, it is common to temporarily turn up a destination table’s write throughput to speed import. But when the table’s write capacity is increased, DynamoDB may do an irreversible split of the partitions underlying the table, spreading the total table capacity evenly across the new generation of tables. Later, if the capacity is reduced, the capacity for each partition is also reduced but the total number of partitions is not, leaving less capacity for each partition. This leaves the table in a state where it much easier for hotspots to overwhelm individual partitions.
- It is important to make sure that DynamoDB [resource limits](http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Limits.html#limits-data-types) are compatible with your dataset and workload. For example, the maximum size value that can be added to a DynamoDB table is 400 KB (larger items can be stored in S3 and a URL stored in DynamoDB). - It is important to make sure that DynamoDB [resource limits](http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Limits.html#limits-data-types) are compatible with your dataset and workload. For example, the maximum size value that can be added to a DynamoDB table is 400 KB (larger items can be stored in S3 and a URL stored in DynamoDB).
- Dealing with time series data in DynamoDB can be challenging. A Global Secondary Index together with down sampling timestamps can be a possible solution as explained [here](https://blogs.aws.amazon.com/bigdata/post/Tx3KPZDXIBJEQ4B/Scaling-Writes-on-Amazon-DynamoDB-Tables-with-Global-Secondary-Indexes).
ECS ECS
--- ---
@ -1282,7 +1283,7 @@ This section covers tips and information on achieving [high availability](https:
### High Availability Gotchas and Limitations ### High Availability Gotchas and Limitations
- **AZ naming** differs from one customer account to the next. Your “us-west-1a” is not the same as another customer’s “us-west-1a” — the letters are assigned to physical AZs randomly per account. This can also be a gotcha if you have multiple AWS accounts. - **AZ naming** differs from one customer account to the next. Your “us-west-1a” is not the same as another customer’s “us-west-1a” — the letters are assigned to physical AZs randomly per account. This can also be a gotcha if you have multiple AWS accounts.
- **Cross-AZ traffic** is not free. At large scale, the costs add up to a significant amount of money. If possible, optimize your traffic to stay within the same AZ as much as possible. - **Cross-AZ traffic** is not free. At large scale, the costs add up to a significant amount of money. If possible, optimize your traffic to stay within the same AZ as much as possible.
Billing and Cost Management Billing and Cost Management
--------------------------- ---------------------------
@ -1336,7 +1337,7 @@ Billing and Cost Management
- Profile your application to figure out its runtime characteristics. That would help give an understanding of the minimum cpu, memory, disk required. Having this information is critical before you try to optimize spot costs. - Profile your application to figure out its runtime characteristics. That would help give an understanding of the minimum cpu, memory, disk required. Having this information is critical before you try to optimize spot costs.
- Once you know the minimum application requirements, instead of resorting to fixed instance types, you can bid across a variety of instance types (that gives you higher chances of getting a spot instance to run your application).E.g., If you know that 4 cpu cores are enough for your job, you can choose any instance type that is equal or above 4 cores and that has the least Spot price based on history. This helps you bid for instances with greater discount (less demand at that point). - Once you know the minimum application requirements, instead of resorting to fixed instance types, you can bid across a variety of instance types (that gives you higher chances of getting a spot instance to run your application).E.g., If you know that 4 cpu cores are enough for your job, you can choose any instance type that is equal or above 4 cores and that has the least Spot price based on history. This helps you bid for instances with greater discount (less demand at that point).
- **Spot price monitoring and intelligence:** - **Spot price monitoring and intelligence:**
- Spot Instance prices fluctuate depending on instance types, time of day, region and availability zone. The AWS CLI tools and API allow you to describe Spot price metadata given time, instance type, and region/AZ. - Spot Instance prices fluctuate depending on instance types, time of day, region and availability zone. The AWS CLI tools and API allow you to describe Spot price metadata given time, instance type, and region/AZ.
- Based on history of Spot instance prices, you could potentially build a myriad of algorithms that would help you to pick an instance type that either - Based on history of Spot instance prices, you could potentially build a myriad of algorithms that would help you to pick an instance type that either
- optimizes cost - optimizes cost
- maximizes availability - maximizes availability