Concurrency Control

Not Supported

SimpleDB does not support concurrency control itself. However, applications can support optimistic concurrency control (OCC) by maintaining a version number attribute and performing a conditional update on the value of this version number.

Data Model

Key/Value

SimpleDB organizes data as a table. Rows represent items and columns represent attributes. Items are attribute-value pairs. A cell is intersection of a row and a column and it can contain empty value or multiple values.

Indexes

Hash Table

SimpleDB does support index but no material shows what kind of index method it applies.

Isolation Levels

Read Committed

SimpleDB maintains multiple copies of each data. A successful write guarantees all copies of data is durable. There are two read consistency options: eventually consistent read and consistent read. A consistent read corresponds to read committed isolation level because it guarantees that the return value is the latest. An eventually consistent read acts like best efforts. It does not ensure that the copy of data is the latest but it is acceptable to increase throughput for some applications.

Joins

Not Supported

Query Compilation

Not Supported

Query Execution

Tuple-at-a-Time Model

No material shows the query execution choice. Since SimpleDB is NoSQL DBMS, I guess it may process one tuple at a time.

Query Interface

Custom API

SimpleDB utilizes REST HTTP API. It is friendly to web based applications.

Storage Architecture

Disk-oriented

No material shows the exact storage methods. I guess it is disk-oriented because it guarantees the durability of data and the simplest way is to store the data on disks.

Storage Model

Custom

No materials show the storage model of SimpleDB. It is based on key-value storage for NoSQL queries.

Stored Procedures

Not Supported

System Architecture

Shared-Nothing

Views

Not Supported