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A query plan (or query execution plan) is a sequence of steps used to access data in a SQL relational database management system. This is a specific case of the relational model concept of access plans. Since SQL is declarative, there are typically many
In such cases, alternative query plans must be compared in terms of their execution time but also in terms of the precision or reliability of the data they generate. Multi-objective query optimization [10] models the cost of a query plan as a cost vector where each vector component represents cost according to a different cost metric. Classical ...
Query optimizer – component of a database management system that attempts to determine the most efficient way to execute a query. Query plan – ordered set of steps used to access or modify information in a SQL relational database management system. Also called a "query execution plan".
The database translates the query into a "query plan" which may vary between executions, database versions and database software. This functionality is called the "query optimizer" as it is responsible for finding the best possible execution plan for the query, within applicable constraints. The SELECT statement has many optional clauses:
Also, while they avoid some pre-compiled SQL, statements add to the complexity of creating an optimal execution plan because not all arguments of the SQL statement are supplied at compile time. Depending on the specific database implementation and configuration, mixed performance results will be seen from stored procedures versus generic ...
Microsoft SQL Server (Structured Query Language) is a proprietary relational database management system developed by Microsoft.As a database server, it is a software product with the primary function of storing and retrieving data as requested by other software applications—which may run either on the same computer or on another computer across a network (including the Internet).
In effect, Pig Latin programming is similar to specifying a query execution plan, making it easier for programmers to explicitly control the flow of their data processing task. [12] SQL is oriented around queries that produce a single result.
A stored procedure, which is also precompiled and stored on the server for later execution, has similar advantages. Unlike a stored procedure, a prepared statement is not normally written in a procedural language and cannot use or modify variables or use control flow structures, relying instead on the declarative database query language.