Query-Evaluation Plan in SQL

Query Evaluation Plan is a program for an abstract machine inside the DBMS. It is produced by the query optimizer. At times this can also be termed as access plan because DBMS decide's how to access the rows. Query evaluation plans are very much similar to relational algebra expressions in most of the systems.

Executing a Query Evaluation Plan :

In many relational algebra expressions it is very necessary to translate expression and also to annotate the translated relational algebra expression with the commands used for stating and evaluating operation. And immediately after translating the user query, the system uses the query program.

Characteristics of Query Evaluation Plan:

• It can also be called the Query Questionnaire.
• Systems must create a query system to fully analyze the query.
• Annotations in the test program sometimes refer to the steps used to perform.
• Related algebra with annotations named Evaluation Primitives containing the instructions needed to evaluate the work.
• There is therefore nothing wrong with the fact that the questionnaire program describes a sequence of previous works that are very useful in questioning.
• The result of the query is generated by the query engine.

Optimization : 

• Since we know that there are different types of questions so the cost of testing will vary, one thing is that the user does not need to write his question correctly because the system does it automatically.
• If the website system produces an effective query program that leads to cost reduction then this type of activity is known as Quiz Development.
• Since all tasks are cost-effective in allocating memory the query caller should have a limited cost analysis for each task.