1.
Using Amazon SimpleDB
with Rails
http://webonrails.com

2.
Amazon SimpleDB
● Database web service advertised as:
● Simple, Flexible, Scalable, Fast, Reliable, Inexpensive
● No RDBMS: no SQL, no joins, no schema,
no referential integrity, no transactions
● Ability to store, process and query data
sets
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3.
Amazon SimpleDB
● HTTP-Interface
● Pricing: Similar to other AWS
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4.
Before we move
Further
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5.
Let, have a look
at
Amazon SimpleDB
Common Terms
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6.
Amazon SimpleDB Common
Terms
● Domain:
storage container ~ table
● Item:
~ table rows accessed by ID ~ primary key
● Attribute:
~ table columns; every item may have a different
set of upto 256 attributes
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7.
Amazon SimpleDB Common
Terms
● Value:
each Attribute may havemultiple Values, always
varchar(1024)[]
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8.
SimpleDB
Domain A
Attributes
Items
Values (multiple)
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9.
PUT (item, 123),
(description, sweater),
(color, blue),
(color, red)
PUT (item, 456),
(description, dress shirt),
(color, white),
(color, blue)
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10.
Amazon SimpleDB API
● Domain level:
● CREATE, LIST, DELETE
● Item level:
● GET, PUT, DELETE attributes with values
● QUERY for unordered item IDs by
attribute values within one domain
● Beware: Eventual Consistency Approach!
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11.
Benefits over traditional databases
● No need to pre-define data types
● 'Size' can be 9 or XL or 1.5
● Add attributes anytime
● Attributes specifically for some items
● Index all data
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12.
API Summary
● CreateDomain — Create a domain(100).
● DeleteDomain — Delete a domain.
● ListDomains — List all domains.
● DomainMetadata — Retrieve information
about the domain.
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13.
API Summary
● PutAttributes — Add or update an item and
its attributes, or add attribute-value pairs to
items that exist already.
● GetAttributes — Retrieve an item and all or
a subset of its attributes and values.
● DeleteAttributes — Delete an item, an
attribute, or an attribute value.
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14.
API Summary
● Query — Query the dataset using a query
expression which specifies value tests on
one or more attributes.
● Supported value tests are:
=, !=, <, > <=, >=, starts-with.
[“price” < “12.00”] INTERSECTION [“color” = “green”].
● Order results using the SORT operator
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15.
API Summary
● QueryWithAttributes — Enables developers
to retrieve all or a subset of the information
associated with items returned as a
response to a particular query.
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16.
SimpleDB vs S3
S3 SimpleDB
● Stores raw data ● Stores indexed data
● Uses higher dense ● Uses less dense
storage drives storage drives
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17.
SimpleDB Limits (Cont...)
● Domain size 10 GB per domain
● Domain size 250,000,000 attribute name-
value pairs
● Domain name 3-255 characters
● Domains per account 100
● Attribute name-value pairs/item 256
● Attribute name length 1024 bytes
● Attribute value length 1024 bytes
● Item name length 1024 bytes
● All UTF-8 characters that are valid in XML documents are
allowed in name/value.
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18.
SimpleDB Limits
● Attributes per PutAttributes operation 100
● Maximum items in query response 250
● Maximum query execution time 5 seconds
● Maximum comparisons per predicate 10
● Maximum predicates per query 10
expression
● Maximum response size for 1MB
QueryWithAttributes
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19.
Working with Numerical Data
● SimpleDB is a schema-less data store
● Everything is stored as a UTF-8 string value
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20.
Working with Numerical Data
● Ensure that every number is positive
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21.
Working with Numerical Data
● Ensure that every number is positive
What about Negative
Numbers?
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22.
Negative Numbers Offsets
● Choose an offset
● That should be arger than the smallest
expected negative number in your data set
● Ex:
● if the smallest expected number in your data set is -12,
choosing offset = 100 might be safe
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23.
Negative Numbers Offsets
The following is a sample original data set.
14.58, -12.7, 20, 65, -23
If you apply an offset of 100 the following is the resulting
data set:
114.58, 87.3, 120, 165, 77
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24.
Zero Padding
● Since simpleDB uses lexicographical
comparisons “10” comes before “2”
● If we zero pad the numbers to five digits,
quot;00002quot; comes before quot;00010quot;
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25.
Zero Padding
● Since simpleDB uses lexicographical
comparisons “10” comes before “2”
● If we zero pad the numbers to five digits,
quot;00002quot; comes before quot;00010quot;
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26.
Dates
● ISO 8601 format
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27.
Query dataset
['attribute1' = 'value1']
intersection
not ['attribute2' = 'value2']
union
['attribute3' = 'value3']
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28.
SimpleDB with Rails
AWS SDB
Proxy Plugin
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29.
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30.
SimpleDB with Rails
● Install aws-sdb gem
● gem install aws-sdb
● Install aws_sdb_proxy plugin:
● script/plugin install
git://github.com/bansalakhil/aws_sdb_proxy.git
*Plugin originaly written by martin.rehfeld@glnetworks.de
http://webonrails.com

31.
AWS SDB Proxy Plugin
● Configure config/aws_sdb_proxy.yml
● development:
aws_access_key_id: <aws key>
aws_secret_access_key: <aws secret key>
port: 8888
● Create new domain on Amazon SimpleDB
● rake aws_sdb:create_domain DOMAIN=MyDataStore
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32.
AWS SDB Proxy Plugin
● Start AWS SDB proxy
● rake aws_sdb:start_proxy_in_foreground
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33.
Mapping RESTful URLs
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34.
Using AWS SDB Proxy Plugin
● Create demo ActiveResource model
class Post < ActiveResource::Base
self.site = quot;http://localhost:8888quot;
self.prefix = quot;/MyDataStore/quot;
end
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35.
Lets try at script/console
>> Article.create(:title => quot;This is my First articlequot;)
=> #<Article:0xb7005d04 @attributes={quot;updated_atquot;=>Sat Dec 13
15:53:30 UTC 2008, quot;titlequot;=>quot;This is my First articlequot;,
quot;idquot;=>601834...98, quot;created_atquot;=>Sat Dec 13 15:53:30 UTC 2008},
@prefix_options={}>
>> a = Article.create(:title => quot;This is my Second articlequot;)
=> #<Article:0xb6fe1f08 @attributes={quot;updated_atquot;=>Sat Dec 13
15:53:52 UTC 2008, quot;titlequot;=>quot;This is my Second articlequot;,
quot;idquot;=>112...9, quot;created_atquot;=>Sat Dec 13 15:53:52 UTC 2008},
@prefix_options={}>
>> a.body = quot;Nothingquot;
>> a.save
=> true
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36.
Lets try at script/console
>> Article.find(:all).size
=> 2
>> Article.find(:all, :from => :query, :params => quot;['title' starts-with 'This
is' ]quot;)
=> [#<Article:0xb6f73080 @attributes={quot;updated_atquot;=>Sat Dec 13
15:53:30 UTC 2008, quot;titlequot;=>quot;This is my First articlequot;, quot;idquot;=>60...98,
quot;created_atquot;=>Sat Dec 13 15:53:30 UTC 2008},
@prefix_options={}>, #<Article:0xb6f7306c
@attributes={quot;updated_atquot;=>Sat Dec 13 15:54:14 UTC 2008,
quot;bodyquot;=>quot;Nothingquot;, quot;titlequot;=>quot;This is my Second articlequot;,
quot;idquot;=>11...79, quot;created_atquot;=>Sat Dec 13 15:53:52 UTC 2008},
@prefix_options={}>]
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37.
References
● http://aws.amazon.com/simpledb/
● http://inside.glnetworks.de
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38.
Thanks
Akhil Bansal
http://webonrails.com
http://webonrails.com