Varrays versus nested tables, PL-SQL Programming

Assignment Help:

Varrays versus Nested Tables

The Nested tables are differing from varrays in the following ways:


1)  Varrays have a maximum size, while nested tables do not.

2)  Varrays are always dense, while nested tables can be sparse. Therefore, you can delete individual elements from a nested table but not from a varray.

3) The Oracle stores varray data in-line (in similar tablespace). But, the Oracle stores nested table data out-of-line in a store table, that is a system-generated database table related with the nested table.

4) When stored in the database, the varrays retain their ordering and subscripts, while nested tables do not.


Which collection type must you use? That totally depends on your wants and the size of the collection. The varray is stored as an opaque object, while a nested table is stored in a storage table with each element mapped to a row in the table. Therefore, if you want efficient queries, then use the nested tables. If you want to retrieve the whole collections as a whole, then use varrays. Though, when collections get very large, it becomes impractical to retrieve more than subsets. Therefore, varrays are better suited for the small collections


Related Discussions:- Varrays versus nested tables

Semidifference via except and join - sql, Semidifference via EXCEPT and JOI...

Semidifference via EXCEPT and JOIN - SQL SELECT * FROM (SELECT StudentId FROM IS_CALLED WHERE Name = 'Devinder' EXCEPT DISTINCT CORRESPONDING SELECT StudentId

Some varray examples-manipulating collections, Some Varray Examples In S...

Some Varray Examples In SQL Plus, assume that you define an object type Project, as described below: SQL> CREATE TYPE Project AS OBJECT ( 2 project_no NUMBER(2), 3 title VARCHA

Parameter and keyword description - fetch statement, Parameter and Keyword ...

Parameter and Keyword Description: cursor_name: This identifies an explicit cursor formerly declared within the present scope. cursor_variable_name: These identif

Difference between 9i & 10g, Difference between 9i & 10G When Oracle r...

Difference between 9i & 10G When Oracle releases any new databases then it are having some discrepancy with them. But 10G is having much difference than oracle 9i has. Oracle

Build a purchases report that matches the general ledger, Great Plains (Mic...

Great Plains (Microsoft Dynamics) Purchases Report Project Description: I want to build a purchases report that matches the General Ledger. presently, when I join the PM20

Example of except operator - sql, Example of EXCEPT Operator - SQL Ex...

Example of EXCEPT Operator - SQL Example, like its counterpart in the theory book, illustrates the convenience of allowing any table expression to be the source for an INSERT

Types of evolution, TYPES OF EVOLUTION - Sequential evolution         ...

TYPES OF EVOLUTION - Sequential evolution                  :                    Minor changes in the gene pool of a population from one generation to the next, with the resul

Using default-declarations in sql, Using DEFAULT You can use the keyword...

Using DEFAULT You can use the keyword DEFAULT rather than that of the assignment operator to initialize the variables. For e.g. the declaration blood_type CHAR := ’O’; it can b

Sql, Write a cursor to open an employee database and fetch the employee rec...

Write a cursor to open an employee database and fetch the employee record whose age is greater than 45

Projection in sql - correct version, Projection in SQL - correct version ...

Projection in SQL - correct version Student StudentId is enrolled on some course. SELECT DISTINCT StudentId FROM IS_ENROLLED_ON In more complicated examples it is someti

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd