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Index files are auxiliary file stored in database used in faster accessing of data , and it is important especially when database file size growing exponentially. Today world storage is not a problem, but retrieval/searching on certain criteria is problem.
Index files- Secondary or auxiliary files that help speed up access in primary files
Indexes or access structure: data structure -- data structure used for fast access.
Primary index: An index structure that is defined on the ordering field (that is used to physically order records on disk in sorted file organization)
Secondary index : used to index field that are neither ordering fields nor key fields(there is no assurance that the file is organized on key field or primary key field). One index entry for every tuple in the data file(dense index) contain the value of the indexed attribute and pointer to the block /record
What happens when Key field is used as index filed in Secondary Index?
- Since the key fields are unique , number of index entries equal to number of records
- Data records need not be sorted on disk
- Fixed length records for index file
What happens when non-Key field is used as index filed in Secondary Index?
- When a non key filed is indexed, indexed field entry need not be unique, there can be duplicate entry.
How to handles these duplicate entry?
There methods are there to handle this duplicate value
- Duplicate index entries
- Variable length records (one value should point more than one records)
- Extra redirection levels
What else can I help you with?
What is the difference between a Primary Key and a Secondary Key?
A Primary Key is a unique identifier for each record in a database table and is used to enforce entity integrity. A Secondary Key is a non-unique index that is used for querying and organizing data efficiently but does not have the constraint of uniqueness.
What is the most common identifier used to index and link database?
The most common identifier used to index and link databases is the primary key. It uniquely identifies each record in a table and is used to establish relationships between different tables in a database.
What is the difference between table of context and index?
A table of contents provides a list of main headings and subheadings in a document or book in the order they appear, helping readers navigate the content. An index, on the other hand, lists specific topics, names, and terms alphabetically with page numbers where they can be found, aiding readers in locating specific information within the document.
What is the difference between stored procedure and index?
As stored procedure in procedural code, which usually calculates or changes some data. An index is a database object which aids in quick location of records because it is internally ordered in a optimized way for the specific key
What is the meaning of supplemental index?
A supplemental index is an additional index created by search engines to include web pages that are not part of the main index. These pages are typically less important or have unique content that is not regularly crawled by search engine bots. The supplemental index is used to ensure a more comprehensive search experience for users.
What is the difference between a Primary Key and a Secondary Key?
A Primary Key is a unique identifier for each record in a database table and is used to enforce entity integrity. A Secondary Key is a non-unique index that is used for querying and organizing data efficiently but does not have the constraint of uniqueness.
What is the difference between primary key and unique index?
Primary key is a type of unique index with no null constraint on the columns involved. There can only be one Primary key whereas you can create other unique indexes on the table.
What is secondary indexes in dbms?
secondary index is a key which is created other than primary key, to speed up processing.
What is the index error in theodolite?
Half of the difference between the two positions is called the "index error".
Is there any difference between index and indicator?
yes there iis
Which secondary school was index 330122037 chosen?
The Index number 330122037 is for LAMU EVANS KAMONDE. It indicates that a Kenya Certificate Of Primary Education was issued. This male candidate was awarded the certificate in Machakos County.
What are the difference between Unicode and ASCII code?
describe the destination index
What is the difference between viscosity and viscosity index?
Viscosity is resistance to flow of oil Viscosity Index is a scale to measure viscosity
What is the difference between a glossary and index?
A glossary defines words, while the index tells what pages certain topics are on in the book.
The lack of Precambrian index fossils is the primary reason that?
correlation between rock units is impossible
Difference between Index File and Index Sequential file?
index file is organized with the help of any key as index number at rondomly but index sequencial file organized with the help of any index sequentialy rajesh patel
What is the difference between mutual funds and index funds?
Index funds are a type of mutual fund that invests in the stocks of a specific market index, attempting to maintain a value per unit that tracks that index.
