BigTable

BigTable is a proprietary high-performance database system of the company Google. It builds among other things on the Google File System (GFS ) and Chubby Lock Service. It is currently for example, when platform-as -a-Service - Service ( PaaS) Google App Engine used.

History

The development of BigTable began in 2004. It is now used by many Google products, such as MapReduce, Google Maps, Google Books, YouTube or Google Earth. Since BigTable databases can be very large, special attention was paid ( by a non- relational structure) scalability ( through support large-scale computer clusters) and speed.

Design

It is characteristic for data stored in BigTable data that frequently records are added, existing records but are rarely changed. A BigTable is basically composed of a large number of rows that are designated by a Datensatzidentifikator. Within a line any number of columns may be defined. In contrast to the relational database can be of different size, the number of columns for each line. Only the so-called Family Columns that the same data type ( such as a link that points to a page ) include must be known at the implementation of the database, but can contain any number of instances per line.

Each table is multidimensional. For versioning, each entry is given a timestamp. Using timestamps can always use the latest version of the data are taken into account, without having to edit or delete older data.

Example

Google itself describes in a publication an example for the use of BigTable by the Google search engine: For every previously scanned by a crawler new website, a row is created in the corresponding BigTable. The first column contains the first content ( HTML syntax) of the page. The multi-dimensionality is created by later versions of the same page and the associated timestamp ( timestamp ). The subsequent columns all come from the same Family Column "anchor ", which contain the URL of another page that links to the appropriate page. Thus, the number of columns are theoretically infinite.