paws: A High Level PHP Library for Amazon Web Services

AWS SimpleDB

Amazon Web Services SimpleDB is well documented on the AWS website. See the SimpleDB Resources page for a list of available documentation. The "main" technical reference can be downloaded as a PDF file.

However, this section of the paws manual will contain some quick reference material that can be useful when developing a SimpleDB design.

Size Limits

SimpleDB has several limits on sizes, some of which are supposed to get bigger after Beta.

10GB of storage per domain

100 domains per customer account

Attributes per Item: 256

Size per Item: 512KB

256 total attribute name-value pairs per item

Attribute names and attribute values can be up to 1024 bytes in length each

max attributes per domain: 250,000,000

max number of attributes per PutAttributes call: 100

max items you can get returned in a query response: 250
(This is hidden by pawsSDB - it will automatically issue queries
as needed until all matches have been made. )

max seconds your query can run: 5

max attribute names per query predicate: 1

max operators per predicate: 5

max predicates per query: 5

approx max get request size in bytes from ec2: 16k

approx max get request size from elsewhere: 4k
Worst case "eventual consistency" - not guaranteed, usually "a few seconds"

	Note
Amazon SimpleDB itself does not enforce a limit on maximum URL length. However, certain network appliances such as proxies and load balancers may enforce certain limits. Depending on the path between your application and the Amazon SimpleDB endpoint, these devices may interfere with very long URLs. Some of these limits are based on number of packets containing the URL instead of its total length in bytes. This means that congested networks, fragmentable packets, or small source packets may adversely affect request with long URLs. Sizes up to 4096 (4k) bytes should be safe from most locations. From EC2, sizes up to 16384 (16k) bytes will likely work. This guidance is based upon best practices and empirical evidence and is not guaranteed to work in all circumstances. If your application demands larger message sizes than a few kilobytes, we recommend using the SOAP interface or REST with HTTP POST which are not subject to such limits. SimpleDB Forum Article

Note

Amazon SimpleDB itself does not enforce a limit on maximum URL length.

However, certain network appliances such as proxies and load balancers
may enforce certain limits. Depending on the path between your
application and the Amazon SimpleDB endpoint, these devices may interfere with
very long URLs. Some of these limits are based on number of packets
containing the URL instead of its total length in bytes. This means that
congested networks, fragmentable packets, or small source packets may
adversely affect request with long URLs.

Sizes up to 4096 (4k) bytes should be safe from most locations. From
EC2, sizes up to 16384 (16k) bytes will likely work.

This guidance is based upon best practices and empirical evidence and
is not guaranteed to work in all circumstances. If your application
demands larger message sizes than a few kilobytes, we recommend using
the SOAP interface or REST with HTTP POST which are not subject to such limits.

SimpleDB Forum Article