Databases and data stores in the cloud

Given the scale of some of these applications, it isn’t surprising that new database technologies are being developed to support this kind of computing.

Some database experts believe that relational database models may have difficulty processing data across large numbers of servers — in other words, when the data is distributed across multiple machines. Performance can be slow when you’re executing complex queries that involve a join across a distributed environment. Additionally, in an old-style database cluster, data must either be replicated across the boxes in the cluster or partitioned between them. According to other database experts, this makes it hard to provision servers on demand.

In response, some large cloud providers have developed their own databases. Here’s a sample listing:

✓ Google Bigtable: This hybrid is sort of like one big table. Because tables can be large, they’re split at row boundaries into tablets, which might be 100 megabytes or so. MapReduce is often used for generating and modifying data stored in Bigtable. Bigtable is also the data storage vehicle behind Google’s App Engine (a platform for developing applications).

✓ Amazon SimpleDB: This Web service is for indexing and querying data. It’s used with two other Amazon products to store, process, and query data sets in the cloud. Amazon likens the database to a spreadsheet in that it has columns and rows with attributes and items stored in each. Unlike a spreadsheet, however, each cell can have multiple values and each item can have its own set of associated attributes. Amazon then automatically indexes the data.

✓ Cloud-based SQL: Microsoft has introduced a cloud-based SQL relational database called SQL Database (SDS). SDS provides data storage by using a relational model in the cloud and access to that data from cloud and client applications. It runs on the Microsoft Azure services platform. The Azure platform is an Internet-scale cloud-services platform hosted in Microsoft data centers; the platform provides an operating system and a set of developer services.

Numerous open-source databases are also being developed:
✓ MongoDB (schema-free, document-oriented data store written in C++)
✓ CouchDB (Apache open-source database)
✓ LucidDB (Java/C++ open-source data warehouse)

Source of Information : cloud computing for dummies 2010 retail ebook distribution


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