Tree-based Indexing Hessam Zakerzadeh

ISAM (Indexed Sequential Access Method) ISAM was originally developed by IBM for mainframe computers Allows records to be accessed: sequentially (in the order they were entered) randomly (with an index)

ISAM (Indexed Sequential Access Method) Static index structure. Data values reside in leaf nodes. Effective when file is not frequently updated.

Leaf pages contain data entries. Non-leaf Pages Leaf Pages Overflow page Primary pages Leaf pages contain data entries.

After Inserting 23*, 48*, 41*, 42* ... Root Index Pages Primary Leaf 40 Pages 20 33 51 63 Primary Leaf 10* 15* 20* 27* 33* 37* 40* 46* 51* 55* 63* 97* Pages 23* 48* 41* Overflow Pages 42*

Give an example of when you would use each element (A or B) for each of the following ‘A versus B’ pairs: A hashed index using Alternative (1) versus heap file organization.

Give an example of when you would use each element (A or B) for each of the following ‘A versus B’ pairs: A hashed index using Alternative (1) versus heap file organization. hashed index : when most of the queries are equality queries. heap file : when a file is scanned in sequential order.

Extendible Hashing versus Linear Hashing.

Extendible Hashing versus Linear Hashing. Extendible Hashing : When data values lead to a skewed distribution Linear Hashing : A large data file requiring a directory to span several pages.

Static Hashing versus Linear Hashing.

Static Hashing versus Linear Hashing. Static Hashing :When the number of records are constant Linear Hashing: When number of records varies, and hash key values are uniformly distributed.

Static Hashing versus ISAM

Static Hashing versus ISAM Static Hashing: When the number records are constant and most of the queries are equality search ISAM :When queries involve range queries

Linear Hashing versus B+ trees

Linear Hashing versus B+ trees Linear Hashing :When queries are equality search B+ trees :When queries are range search