Organization of Records in Files
In a heap file organization a record can be placed anywhere in the file where there is space. There is no ordering of records and there is a single relation for each relation. In hashing file organization a hash function is computed on some attribute of each record. The result specifies in which block of the file the record should be placed. Sequential file Organization store records in sequential order based on the value of the search key of each record. Sequential file organization is designed for efficient processing of records in sorted order based on search key. The sequential file organization is suitable for applications that require sequential processing of the entire file. The records in the file are ordered by a search-key. A search key is an attribute or set of attributes. For fast retrieval of records in search key order records are linked together by pointer. For insertion we must follow the following rule: Locate the position where the record is to be inserted: If there is free space insert there. If there is no free space insert the record in an overflow block. In either case, pointer chain must be updated. For deletion we must use pointer chains. There is a need to re-organize the file from time to time to restore sequential order.
Summary
In a heap file organization a record can be placed anywhere in the file where there is space. There is no ordering of records and there is a single relation for each relation. In hashing file organization a hash function is computed on some attribute of each record. The result specifies in which block of the file the record should be placed. Sequential file Organization store records in sequential order based on the value of the search key of each record. Sequential file organization is designed for efficient processing of records in sorted order based on search key. The sequential file organization is suitable for applications that require sequential processing of the entire file. The records in the file are ordered by a search-key. A search key is an attribute or set of attributes. For fast retrieval of records in search key order records are linked together by pointer. For insertion we must follow the following rule: Locate the position where the record is to be inserted: If there is free space insert there. If there is no free space insert the record in an overflow block. In either case, pointer chain must be updated. For deletion we must use pointer chains. There is a need to re-organize the file from time to time to restore sequential order.
Things to Remember
- In a heap file organization a record can be placed anywhere in the file where there is space. There is no ordering of records and there is a single relation for each relation.
- In hashing file organization a hash function is computed on some attribute of each record. The result specifies in which block of the file the record should be placed.
- Sequential file Organization store records in sequential order based on the value of the search key of each record.
- Sequential file organization is designed for efficient processing of records in sorted order based on search key. The sequential file organization is suitable for applications that require sequential processing of the entire file.
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Subjective Questions
Q1:
Define Duodenal atresia.
Type: Very_short Difficulty: Easy
<p>Duodenal atresia or stenosis is a rare congenital digestive disorder that usually occurs for no apparent reason (sporadically). However, a few cases of duodenal atresia have been inherited as an autosomal recessive genetic trait.</p>
Q2:
List the sign and symptoms of duodenal atresia ?
Type: Short Difficulty: Easy
<li>Upper abdominal swelling may or may not be present</li>
<li>Early vomiting of large amounts, which may be greenish (containing bile)</li>
<li>Continued vomiting even when infant has not been fed for several hours</li>
<li>Absent urination after first few voidings</li>
<li>Absent bowel movements after first few meconium stools</li>
</ul>
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Organization of Records in Files
Organization of Records in Files
Heap File Organization
In heap file organization a record can be placed anywhere in the file where there is space. There is no ordering of records and there is a single relation for each relation.
Hashing file Organization
In hashing file organization a hash function is computed on some attribute of each record. The result specifies in which block of the file the record should be placed.
Sequential file Organization
Sequential file Organization store records in the sequential order based on the value of the search key of each record.
Sequential File Organization
This file organization is designed for efficient processing of records in the sorted order based on search key. The sequential file organization is suitable for applications that require sequential processing of the entire file. The records in the file are ordered by a search-key. A search key is an attribute or set of attributes. For fast retrieval of records in search key, order records are linked together by a pointer.
For insertion, we must follow the following rule: Locate the position where the record is to be inserted
- If there is free space insert there.
- If there is no free space insert the record in an overflow block.
- In either case, pointer chain must be updated.
For deletion, we must use pointer chains. There is a need to re-organize the file from time to time to restore sequential order.
References:
- H.F.Korth and A. Silberschatz,"Database system concepts",McGraw Hill,2010
- A.K.Majumdar and p, Bhatt acharya,"Database Management Systems",Tata McGraw Hill,India,2004
- F.Korth, Henry. Database System Concepts. 6th edition.
Lesson
File Structure and Hashing
Subject
Computer Engineering
Grade
Engineering
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