Amazon SimpleDB Functionality

Amazon SimpleDB provides a simple web services interface to create and store multiple data sets, query your data easily, and return the results. Your data is automatically indexed, making it easy to quickly find the information that you need. There is no need to pre-define a schema or change a schema if new data is added later. And scale-out is as simple as creating new domains, rather than building out new servers.

To use Amazon SimpleDB you:

• Build your data set

  • Choose a Region for your Domain(s) to optimize for latency, minimize costs, or address regulatory requirements. Amazon SimpleDB is currently available in the US East (Northern Virginia), US West (Northern California), EU (Ireland), and Asia Pacific (Singapore) Regions.
  • Use CreateDomain, DeleteDomain, ListDomains, DomainMetadata to create and manage query domains
  • Use Put, Batch Put, & Delete to create and manage the data set within each query domain

• Retrieve your data

  • Use GetAttributes to retrieve a specific item
  • Use Select to query your data set for items that meet specified criteria

• Pay only for the resources that you consume

Service Highlights

Low touch – The service allows you to focus fully on value-added application development, rather than arduous and time-consuming database administration. Amazon SimpleDB automatically manages infrastructure provisioning, hardware and software maintenance, replication and indexing of data items, and performance tuning.

Scalable – The service simply responds to changes in request volume to your Domain(s), charging you only for the resources actually consumed in serving traffic. If your data set outgrows a single domain, or if you desire even higher throughput, you can take advantage of Amazon SimpleDB’s horizontal scale-out architecture. Designed with parallelism in mind, you can easily spread your data set and requests across additional machine resources by creating additional domains.

Highly available – Amazon SimpleDB automatically creates multiple geographically distributed copies of each data item you store. This provides high availability and durability – in the unlikely event one replica fails, Amazon SimpleDB can failover to another replica in the system.

Flexible – As your business changes or application evolves, you can easily reflect these changes in Amazon SimpleDB without worrying about breaking a rigid schema or needing to refactor code – simply add another attribute to your Amazon SimpleDB data set when needed. You can also choose between consistent or eventually consistent read requests, gaining the flexibility to match read performance (latency and throughput) and consistency requirements to the demands of your application, or even disparate parts within your application.

Fast – Amazon SimpleDB provides quick, efficient storage and retrieval of your data to support high performance web applications. Applications running fully within the Amazon cloud (e.g., an Amazon SimpleDB request originating from an application running on Amazon EC2), will provide near-LAN latency.

Simple to use – Amazon SimpleDB provides streamlined access to the store and query functions that traditionally are achieved using a relational database cluster – while leaving out other complex, often-unused database operations. The service allows you to quickly add data and easily retrieve or edit that data through a simple set of API calls.

Designed for use with other Amazon Web Services – Amazon SimpleDB is designed to integrate easily with other AWS services such as Amazon S3 and EC2, providing the infrastructure for creating web-scale applications. For example, developers can run their applications in Amazon EC2 and store their data objects in Amazon S3. Amazon SimpleDB can then be used to query the object metadata from within the application in Amazon EC2 and return pointers to the objects stored in Amazon S3. Developers can also use Amazon SimpleDB with Amazon RDS for applications that have relational and non-relational database needs. Data transferred between Amazon SimpleDB and other Amazon Web Services within the same Region is free of charge.

Secure – Amazon SimpleDB provides an https end point to ensure secure, encrypted communication between your application or client and your domain. In addition, through integration with AWS Identity and Access Management, you can establish user or group-level control over access to specific SimpleDB domains and operations.

Inexpensive – Amazon SimpleDB passes on to you the financial benefits of Amazon’s scale. You pay only for resources you actually consume. For Amazon SimpleDB, this means data store reads and writes are charged by compute resources consumed by each operation, and you aren’t billed for compute resources when you aren’t actively using them (i.e. making requests).

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• AWS Premium Support
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Detailed Description

The Data Model: Domains, Items, Attributes and Values

The data model used by Amazon SimpleDB makes it easy to store, manage and query your structured data. Developers organize their data-set into domains and can run queries across all of the data stored in a particular domain. Domains are collections of items that are described by attribute-value pairs.

Think of these terms as analogous to concepts in a traditional spreadsheet table. For example, take the details of a customer management database shown in the table below and consider how they would be represented in Amazon SimpleDB. The whole table would be your domain named “customers.” Individual customers would be rows in the table or items in your domain. The contact information would be described by column headers (attributes). Values are in individual cells. Now imagine the records below are new customers you would like to add to your domain.

In Amazon SimpleDB, to add the records above, you would PUT the CustomerIDs into your domain along with the attribute-value pairs for each of the customers. Without the specific syntax, it would look something like this:

PUT (item, 123), (First name, Bob), (Last name, Smith), (Street address, 123 Main St.), (City, Springfield), (State, MO), (Zip, 65801), (Telephone, 222-333-4444) PUT (item, 456), First name, James), (Last name, Johnson), (Street address, 456 Front St.), (City, Seattle), (State, WA), (Zip, 98104), (Telephone, 333-444-5555)

Amazon SimpleDB differs from tables of traditional databases in important ways. You have the flexibility to easily go back later on and add new attributes that only apply to certain records. For example, imagine you begin to capture your customers’ email addresses to enable real-time alerts on order status. Rather than rebuilding your “customer” table, re-writing your queries, rebuilding your indices, and so on, you would simply add the new records and any additional attributes to your existing “customers” domain. The resulting domain might look something like this:

API Summary

Amazon SimpleDB provides a small number of simple API calls which implement writing, indexing and querying data. The interface and feature set are intentionally focused on core functionality, providing a basic API for developers to build upon and making the service easy to learn and simple to use.

• CreateDomain — Create a domain that contains your dataset.
• DeleteDomain — Delete a domain.
• ListDomains — List all domains.
• DomainMetadata — Retrieve information about creation time for the domain, storage information both as counts of item names and attributes, as well as total size in bytes.
• PutAttributes — Add or update an item and its attributes, or add attribute-value pairs to items that exist already. Items are automatically indexed as they are received.
• BatchPutAttributes — For greater overall throughput of bulk writes, perform up to 25 PutAttribute operations in a single call.
• DeleteAttributes — Delete an item, an attribute, or an attribute value.
• GetAttributes — Retrieve an item and all or a subset of its attributes and values.
• Select — Query the data set in the familiar, “select target from domain_name where query_expression” syntax. Supported value tests are: =, !=, <, > <=, >=, like, not like, between, is null, is not null, and every (). Example: select * from mydomain where every(keyword) = ‘Book’. Order results using the SORT operator, and count items that meet the condition(s) specified by the predicate(s) in a query using the Count operator.

Note: Amazon SimpleDB has been integrated with AWS Identity and Access Management to enable fine-grained control over Amazon SimpleDB resources. Through integration with AWS Identity and Access Management, an AWS Account signed up to use SimpleDB can create multiple Users. In turn, these Users may be granted SimpleDB API level permissions to access the SimpleDB domains owned by the AWS Account. See the AWS Identity and Access Management detail page for additional details.

Consistency Options

Amazon SimpleDB stores multiple geographically distributed copies of each domain to enable high availability and data durability. A successful write (using PutAttributes, BatchPutAttributes, DeleteAttributes, CreateDomain or DeleteDomain) means that all copies of the domain will durably persist. Amazon SimpleDB supports two read consistency options: eventually consistent reads and consistent reads.

• Eventually Consistent Reads (Default) — the eventual consistency option maximizes your read performance (in terms of low latency and high throughput). However, an eventually consistent read (using Select or GetAttributes) might not reflect the results of a recently completed write (using PutAttributes, BatchPutAttributes, DeleteAttributes). Consistency across all copies of data is usually reached within a second; repeating a read after a short time should return the updated data.

• Consistent Reads — in addition to eventual consistency, Amazon SimpleDB also gives you the flexibility and control to request a consistent read if your application, or an element of your application, requires it. A consistent read (using Select or GetAttributes with ConsistentRead=true) returns a result that reflects all writes that received a successful response prior to the read.

By default, GetAttributes and Select perform an eventually consistent read. Since a consistent read can potentially incur higher latency and lower read throughput it is best to use it only when an application scenario mandates that a read operation absolutely needs to read all writes that received a successful response prior to that read. For all other scenarios the default eventually consistent read will yield the best performance. Note also that Amazon SimpleDB allows you to specify consistency settings for each individual read request, so the same application could have disparate parts following different consistency settings.

Transactions

Amazon SimpleDB is not a relational database and sacrifices complex transactions and relations (i.e., joins) in order to provide unique functionality and performance characteristics. However, Amazon SimpleDB does offer transactional semantics such as:

• Conditional Puts/Deletes — enable you to insert,replace, or delete values for one or more attributes of an item if the existing value of an attribute matches the value you specify. If the value does not match or is not present, the update is rejected. Conditional Puts/Deletes are useful for preventing lost updates when different sources write concurrently to the same item.

Conditional puts and deletes are exposed via the PutAttributes and DeleteAttributes APIs by specifying an optional condition with an expected value. For example, if your application was reserving seats or selling tickets to an event, you might allow a purchase (i.e., write update) only if the specified seat was still available (the optional condition). These semantics can also be used to implement functionality such as counters, inserting an item only if it does not already exist, and optimistic concurrency control (OCC). An application can implement OCC by maintaining a version number (or a timestamp) attribute as part of an item and by performing a conditional put/delete based on the value of this version number.

To learn more about transactional semantics or consistency with Amazon SimpleDB, please refer to the Amazon SimpleDB Developer Guide or Consistency Enhancements Whitepaper.

Choosing an AWS Database Solution

Amazon Web Services provides a number of database alternatives for developers. Amazon RDS enables you to run a fully featured relational database while offloading database administration; Amazon SimpleDB provides simple index and query capabilities with seamless scalability; and using one of our many relational database AMIs on Amazon EC2 and Amazon EBS allows you to operate your own relational database in the cloud. There are important differences between these alternatives that may make one more appropriate for your use case.

Amazon RDS

If your application requires relational storage, but you want to reduce the time you spend on database management, Amazon RDS automates common administrative tasks to reduce your complexity and total cost of ownership. Amazon RDS automatically backs up your database and maintains your database software, allowing you to spend more time on application development. With the native database access Amazon RDS provides, you get the programmatic familiarity, and tooling and application compatibility, of a traditional relational database. You also benefit from the flexibility of being able to scale the compute resources or storage capacity associated with your relational database instance via a single API call.

With Amazon RDS, you still control the database settings that are specific to your business. This includes building a relational schema to fit your use case, creating indices, and tuning the performance of your database to your application’s workflow. You also take an active role in the scaling decisions for your database – you tell the service when you want to add more storage or change to a larger or smaller DB Instance class.

We recommend Amazon RDS for customers who:

• Have existing or new applications, code, or tools that require a relational database
• Want native access to a MySQL relational database, but prefer to offload the infrastructure management and database administration to AWS
• Like the flexibility of being able to scale their database compute and storage resources with an API call, and only pay for the infrastructure resources they actually consume

Amazon EC2 – Relational Database AMIs

Developers may use a number of leading relational databases on Amazon EC2. An Amazon EC2 instance can be used to run a database, and the data can be stored within an Amazon Elastic Block Store (Amazon EBS) volume. Amazon EBS is a fast and reliable persistent storage feature of Amazon EC2. By designing, building, and managing their own relational database on Amazon EC2, developers avoid the friction of provisioning and scaling their own infrastructure while gaining access to a variety of standard database engines over which they can exert full administrative control. Available AMIs include IBM DB2, Microsoft SQL Server, MySQL, Oracle, PostgreSQL, Sybase, and Vertica.

We recommend Amazon EC2 Relational Database AMIs for customers who:

• Wish to select from a wide variety of database engines
• Want to exert complete administrative control over their database server

Amazon SimpleDB

For database implementations that do not require a relational model, and that principally demand index and query capabilities, Amazon SimpleDB eliminates the administrative overhead of running a highly-available production database, and is unbound by the strict requirements of a RDBMS. With Amazon SimpleDB, you store and query data items via simple web services requests, and Amazon SimpleDB does the rest. In addition to handling infrastructure provisioning, software installation and maintenance, Amazon SimpleDB automatically indexes your data, creates geo-redundant replicas of the data to ensure high availability, and performs database tuning on customers’ behalf. Amazon SimpleDB also provides no-touch scaling. There is no need to anticipate and respond to changes in request load or database utilization; the service simply responds to traffic as it comes and goes, charging only for the resources consumed. Finally, Amazon SimpleDB doesn’t enforce a rigid schema for data. This gives customers flexibility – if their business changes, they can easily reflect these changes in Amazon SimpleDB without any schema updates or changes to the database code.

However, Amazon SimpleDB is not a relational database, and does not offer some features needed in certain applications, e.g. complex transactions or joins.

We recommend Amazon SimpleDB for customers who:

• Principally utilize index and query functions rather than more complex relational database functions
• Don’t want any administrative burden at all in managing their structured data
• Want a service that scales automatically up or down in response to demand, without user intervention
• Require the highest availability and can’t tolerate downtime for data backup or software maintenance

More Information

Visit the Running Databases on AWS page for more detailed information on the various database alternatives for your applications.

Data Storage in Amazon SimpleDB vs. Data Storage in Amazon S3

Unlike Amazon S3, Amazon SimpleDB is not storing raw data. Rather, it takes your data as input and expands it to create multiple indices, thereby enabling you to quickly query that data. Additionally, Amazon S3 and Amazon SimpleDB use different types of physical storage. Amazon S3 uses dense storage drives that are optimized for storing larger objects inexpensively. Amazon SimpleDB stores smaller bits of data and uses less dense drives that are optimized for data access speed.

In order to optimize your costs across AWS services, large objects or files should be stored in Amazon S3, while smaller data elements or file pointers (possibly to Amazon S3 objects) are best saved in Amazon SimpleDB. Because of the close integration between services and the free data transfer within the AWS environment, developers can easily take advantage of both the speed and querying capabilities of Amazon SimpleDB as well as the low cost of storing data in Amazon S3, by integrating both services into their applications.

Amazon SimpleDB currently enables individual domains to grow up to 10 GB each. If your data set is larger than 10 GB, simply take advantage of Amazon SimpleDB’s scale-out architecture and spread your data over multiple domains. Since Amazon SimpleDB is designed with parallelism in mind, spreading your data over more domains will also increase your write and read throughput potential. You are initially allocated a maximum of 100 domains; please complete this form if you require additional domains.

For more information on how many developers benefit from using Amazon SimpleDB in conjunction with Amazon S3, click here.

Estimating Your Storage Costs

With Amazon SimpleDB, the best way to predict the size of your structured data storage is as follows:

Raw byte size (GB) of all item IDs + 45 bytes per item + Raw byte size (GB) of all attribute names + 45 bytes per attribute name + Raw byte size (GB) of all attribute-value pairs + 45 bytes per attribute-value pair

To calculate your estimated monthly storage cost for the US East (Northern Virginia) Region, take the resulting size in GB and multiply by $0.25. Alternatively, for the EU (Ireland) Region, Asia Pacific (Singapore), or the US West (Northern California) Region, take the resulting size in GB and multiply by $.275.

Machine Utilization Example

Amazon SimpleDB measures the machine utilization of each request and charges based on the amount of machine capacity used to complete the particular request (SELECT, GET, PUT, etc.), normalized to the hourly capacity of a circa 2007 1.7 GHz Xeon processor. Machine utilization is driven by the amount of data (# of attributes, length of attributes) processed by each request. A GET operation that retrieves 256 attributes will use more resources than a GET that retrieves only 1 attribute. A multi-predicate SELECT that examines 100,000 attributes will cost more than a single predicate query that examines 250.

In the response message for each request, Amazon SimpleDB returns a field called Box Usage. Box Usage is the measure of machine resources consumed by each request. It does not include bandwidth or storage. Box usage is reported as the portion of a machine hour used to complete a particular request. For the US East (Northern Virginia) Region, the cost of an individual request is Box Usage (expressed in hours) * $0.14 per Amazon SimpleDB Machine hour. The cost of all your requests is the sum of Box Usage (expressed in hours) * $0.14.

For example, if over the course of a month, the sum of the Box Usage for your requests uses the equivalent of one 1.7 GHz Xeon processor for 9 hours, your charge will be:

9 hours * $0.14 per Amazon SimpleDB Machine hour = $1.26.

If your query domains are located in the EU (Ireland) Region, Asia Pacific (Singapore), or US West (Northern California) Region, Amazon SimpleDB Machine hours are priced at $.154 per Machine hour, and all cost calculations should be adjusted accordingly.

Getting Started

The best way to understand Amazon SimpleDB is to work through the Getting Started Guide, part of our Technical Documentation. Within a few minutes, you will be able to create your domain and start building your index!

Intended Usage and Restrictions

Your use of this service is subject to the Amazon Web Services Customer Agreement