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

Opening a cursor variable, Opening a Cursor Variable The OPEN-FOR stat...

Opening a Cursor Variable The OPEN-FOR statement relates a cursor variable with the multi-row query, executes the query, and then identifies the result set. The syntax for ope

Using limit - collection method, Using LIMIT For nested tables, that h...

Using LIMIT For nested tables, that have no maximum size, the LIMIT returns NULL. For varrays, the LIMIT returns the maximum number of elements that a varray can have (that yo

Using commit, Using COMMIT The COMMIT statements end the present trans...

Using COMMIT The COMMIT statements end the present transaction and make permanent any changes made during that transaction. Till you commit the changes, other users cannot acc

Iterative control: loop statement, Iterative Control: LOOP  Statements T...

Iterative Control: LOOP  Statements The LOOP statement executes a series of statements multiple times. There are 3 forms of LOOP statements: LOOP, WHILE-LOOP, & FOR-LOOP. LOOP

Prepare a slq project, Project Description: I want to write some SQL st...

Project Description: I want to write some SQL statements. The things I need are between pages 5-7. The only problem is that i want it till tomorrow. Skills required is SQL

What is a collection, What Is a Collection The collection is an ordered...

What Is a Collection The collection is an ordered group of elements, all of similar type (for e.g. the grades for a class of students). Each element has a unique subscript whic

Avoiding collection exceptions, Avoiding Collection Exceptions   In ma...

Avoiding Collection Exceptions   In many cases, if you reference a nonexistent collection element, then PL/SQL raises a predefined exception. Consider the illustration shown b

Iterative control:exit statements, EXIT The EXIT statement forces a loop...

EXIT The EXIT statement forces a loop to done unconditionally. Whenever an EXIT statement is encountered, the loop is done immediately and controls the passes to the next statem

Cursor variables, What Are Cursor Variables  ? The Cursor variables ar...

What Are Cursor Variables  ? The Cursor variables are like C or Pascal pointers that hold the memory location (address) of some item rather of the item itself. Therefore, decl

Join and and in sql, JOIN and AND in SQL In this Section is all about ...

JOIN and AND in SQL In this Section is all about one operator, JOIN. SQL's closest counterpart, NATURAL JOIN, has already been covered. Here we look at several other "join" op

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