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Database tuning describes a group of activities used to optimize and homogenize the performance of a database.It usually overlaps with query tuning, but refers to design of the database files, selection of the database management system (DBMS) application, and configuration of the database's environment (operating system, CPU, etc.).
Codd's twelve rules [1] are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).
This algorithm is usually applied for updates able to commit in a short period of time, ranging from couple of milliseconds to couple of minutes. There are also long-lived distributed transactions, for example a transaction to book a trip, which consists of booking a flight, a rental car and a hotel.
According to computer scientist Eric Brewer of the University of California, Berkeley, the theorem first appeared in autumn 1998. [9] It was published as the CAP principle in 1999 [10] and presented as a conjecture by Brewer at the 2000 Symposium on Principles of Distributed Computing (PODC). [11]
Altibase is a hybrid DBMS that combines an in-memory database with a conventional disk-resident database in a single unified engine. It supports full ACID properties and standard connectivity interfaces such as JDBC and ODBC, as well as interoperability.
If the last name is larger than 10 letters, using the SUBSTR function [9] we change the last_name column value to an abbreviation. CREATE OR REPLACE TRIGGER phone_book_insert BEFORE INSERT ON phone_book FOR EACH ROW WHEN ( LENGTH ( new . last_name ) > 10 ) BEGIN : new . last_name : = SUBSTR (: new . last_name , 0 , 1 ); END ;
The CAP theorem is based on three trade-offs, one of which is "atomic consistency" (shortened to "consistency" for the acronym), about which the authors note, "Discussing atomic consistency is somewhat different than talking about an ACID database, as database consistency refers to transactions, while atomic consistency refers only to a property of a single request/response operation sequence.
A SQL query to a modern relational DBMS does more than just selections and joins. In particular, SQL queries often nest several layers of SPJ blocks (Select-Project-Join), by means of group by, exists, and not exists operators. In some cases such nested SQL queries can be flattened into a select-project-join query, but not always. Query plans ...