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The dbm library stores arbitrary data by use of a single key (a primary key) in fixed-size buckets and uses hashing techniques to enable fast retrieval of the data by key. The hashing scheme used is a form of extendible hashing , so that the hashing scheme expands as new buckets are added to the database, meaning that, when nearly empty, the ...
To gather the necessary information for the logs, two data structures have to be maintained: the dirty page table (DPT) and the transaction table (TT). The dirty page table keeps record of all the pages that have been modified, and not yet written to disk, and the first Sequence Number that caused that page to become dirty.
A relational DBM uses related data fields (columns) to correlate information between tables. [5] For example, two tables, transaction_user and transaction_amount, would both contain the column "key", and keys between tables would match, making it easy to find both the user and the amount of a specific transaction if the key is known.
Isolation is typically enforced at the database level. However, various client-side systems can also be used. It can be controlled in application frameworks or runtime containers such as J2EE Entity Beans [2] On older systems, it may be implemented systemically (by the application developers), for example through the use of temporary tables.
Encryption can be employed to enhance the security of data stored in a database by converting the information into an unreadable format using an algorithm. The encrypted data can only be accessed and deciphered with a decryption key, ensuring that even if the database is compromised, the information remains confidential.
The database schema is the structure of a database described in a formal language supported typically by a relational database management system (RDBMS). The term " schema " refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases ).
One technique for evaluating database security involves performing vulnerability assessments or penetration tests against the database. Testers attempt to find security vulnerabilities that could be used to defeat or bypass security controls, break into the database, compromise the system etc. Database administrators or information security administrators may for example use automated ...
The following examples further illustrate the ACID properties. In these examples, the database table has two columns, A and B. An integrity constraint requires that the value in A and the value in B must sum to 100. The following SQL code creates a table as described above: