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

Rollback behavior - bulk bind performance improvement, Rollback Behavior ...

Rollback Behavior When a FORALL statement fails, the database changes are rolled back to an implicit savepoint marked before each of the SQL statement execution. The Changes t

Object type in pl/sql, Object Type: The object type is a user-define...

Object Type: The object type is a user-defined composite datatype which encapsulates a data structure along with the functions and procedures required to manipulate the data

When are constraints checked - sql, When Are Constraints Checked Unde...

When Are Constraints Checked Under the model constraints are conceptually checked at all statement boundaries (and only at statement boundaries). By default the same is true

Updating tables in sql, Updating Tables in SQL The topic of updating b...

Updating Tables in SQL The topic of updating by describing the assignment operator, ":=" in Tutorial D. SQL uses a different syntax for assignment, using the key word SET and

Cursors in pl/sql, Cursors The Oracle uses work areas to execute the SQ...

Cursors The Oracle uses work areas to execute the SQL statements and to store process information. A PL/SQL construct known as the cursor. Let's you assume name a work area and

Using first and last - collection method, Using FIRST and LAST FIRST a...

Using FIRST and LAST FIRST and LAST return the first and last (minimum and maximum) index numbers in a collection. When the collection is empty, the FIRST and LAST return NULL

Existential quantification - sql, Existential Quantification - SQL Ex...

Existential Quantification - SQL Existential quantification-stating that something is true of at least one object under consideration-can be expressed by OR(r,c), meaning tha

Obtaining a natural join by specifying the common columns, Obtaining a natu...

Obtaining a natural join by specifying the common columns Synatax: SELECT * FROM IS_CALLED JOIN IS_ENROLLED_ON USING ( StudentId ) However, a named columns join doe

Parameter and keyword description - records, Parameter and Keyword Descript...

Parameter and Keyword Description: record_type_name: This identifies the user-defined type specifier that is used in the subsequent declarations of the records. NOT N

Name resolution - pl/sql, Name Resolution   During the compilation, th...

Name Resolution   During the compilation, the PL/SQL compiler relates identifiers like the name of a variable with an address or memory location, actual value, or datatype. Th

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