The Berkley Database

Introduction to Berkeley DB

Berkeley DB is an open source library which provides a high performance embedded data management with various programming languages. This library provides a simple function-call API for data access and management. Berkeley DB is originated at the University of California, Berkeley and from the beginning it is distributed under open source license agreement for that the complete source code for is freely available for download and use.

Berkeley DB provides an embedded database management because it directly links into the application itself and runs in the same address space. This eliminates the need to inter-process communications in the internal machine and between external machines over the network. For that the cost of maintaining a communication between processes is replaced with the cost of making function calls since the latter one is much less costly. Once Berkeley DB is linked to the application the end user generally does not know that there's a database present at all.

Berkeley DB provides a simple function-call API for the programming languages like C, C++, Java, Perl, Tcl, Python, and PHP. For that any system built in these language can easily reference to Berkeley DB library and create a database management. This library handles all the database operations inside, even the low-level services like locking, transaction logging, shared buffer management, memory management. This enables multiple processes or threads to use the database at the same time.

Data Management with Berkeley DB

Berkeley DB provides a relatively simple data management when compared to the commonly used modern database management software products.

All the records in Berkeley DB is as treated as key-value pairs in which value part is simply the payload of the key. Berkeley DB only operates on the key part of the record. There are only a few logical record-operations can be performed in Berkeley DB. These are:

   * Inserting a record
   * Deleting a record
   * Finding a record by its key
   * Updating a record

There is no specific record format in Berkeley DB. Key-value pairs are byte strings that can be either in fixed or variable length. Database developers can put data structures into the database before converting them to any record format. However, in order to perform storage and retrieval operations applications should know what the structure of key and value is. That is because Berkeley DB does not holds this information and should always be fed by the application. Even if Berkeley DB has this disadvantage of not providing the programmer the information on the contents or the structure of the values, it literally is limitless on the data types that can be stored in a Berkeley DB database. Berkeley is able to work on any data type determined by the programmer no matter how complex it is.

In Berkeley DB the size of the keys and values can be up to four gigabytes for that a single record can store images, audio/video streams or other large data types. Management of this larger values requires no specific management. They are simply broken into page-sized chunks, and reassembled on demand when needed.