Amazon SimpleDB

Developer Brown BagJakub, Rande, Stefano, Tim, & Brett

Agenda• Recap/clarification on recent releases

• BatchPutAttributes• Long running Select queries• Select Count

• Step-by-step SimpleDB tutorial

• Your questions

BatchPutAttributes API• Natural extension to PutAttributes• Up to 25 items per batch• Up to 256 attributes per item

• Same as PutAttributes• One megabyte maximum request size• Improved throughput compared to PutAttributes

• Fewer round trips with SimpleDB• Server side optimizations

BatchPutAttributes parameters• Rest:

Item.X.ItemName=ItemNameItem.X.Attribute.Y.Name=AttributeNameItem.X.Attribute.Y.Value=AttributeValueItem.X.Attribute.Y.Replace=true/falseX: 0-24 itemsY: 0-255 attributes per item

• Soap: <Item>

<ItemName>...</ItemName><Attribute><Name>...</Name><Value>...</Value><Replace>...</Replace> </Attribute>

</Item>

• Replace flag is optional and defaults to FALSE • Specify only when strictly necessary

More on BatchPutAttributes• BatchPutAttributes can be executed in

parallel• Can achieve even higher throughput• Requests throttled aggressively (503) if excessive

parallelism• Excessive depends on dataset

• All or nothing semantics• API Call either accepted or rejected in its entirety• Call rejected when throttled (503)• Call rejected when limit exceeded

Long Running Selects• Query, QueryWithAttributes and Select all have a 5

seconds timeout• When timeout elapses

• Query and QueryWithAttributes return 408 (timeout) error and no data

• Select returns partial result set accumulated so far and NextToken to pick up where it left off

• Individual partial result set could be empty• Client responsible for combining result sets• Select can complete even very complex queries over

multiple iterations

Select Count(*)• Counts number of items that qualify predicate

• Server side counting much more efficient

• Count all items in domain: select count(*) from MyDomain

• Count blue eyes in domain: select count(*) from MyDomain where EyeColor = 'blue'

• Count up to 500 blue eyes in domain: select count(*) from MyDomain where EyeColor = 'blue' limit 500

Count(*) and timeouts• 5 second timeout enforced for Count(*) as well

• Select will return NextToken together with partial count

• Partial counts must be accumulated by client1. Client issues “select count(*) from MyDomain” with no token2. SimpleDB returns 20,000 and NextToken T13. Client issues “select count(*) from MyDomain” with NextToken T14. SimpleDB returns 50,000 and NextToken T25. Client issues “select count(*) from MyDomain” with NextToken T26. SimpleDB returns 35,000 and no NextToken7. Final count is 20,000 + 50,000 + 35,000 = 105,000

Interchangeable NextToken• NextToken returned by Count(*) can be used for Select

• WHERE and ORDER BY clauses must match

• Can be used to efficiently bypass records in result set• Return 100 items after the first 100,000 for

select * from MyDomain where EyeColor = 'blue' and Age > '30’ order by Age1. Client issues with no token

select Count(*) from MyDomain where EyeColor = 'blue' and Age > '30' order by Age limit 100000

2. SimpleDB returns 65,000 and NextToken T13. Client issues with NextToken T1

select Count(*) from MyDomain where EyeColor = 'blue' and Age > '30' order by Age limit 35000

4. SimpleDB returns 35,000 and NextToken T25. Client issues with NextToken T2

select * from MyDomain where EyeColor = 'blue' and Age > '30' order by Age limit 100

SimpleDB Tutorial

AWS Evangelist Mike Culver

Questions?