Sorted files files compacted ayer dele6ons indexes

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: e ignore CPU costs, for simplicity: –  –  –  –  –  B: The number of data pages R: Number of records per page D: (Average) 6me to read or write disk page Measuring number of page I/O’s ignores gains of pre ­fetching a sequence of pages; thus, even I/O cost is only approximated. Average ­case analysis; based on several simplis6c assump6ons.   Good enough to show the overall trends! Comparing File Organiza6ons •  •  •  •  •  Heap files (random order; insert at eof) Sorted files, sorted on <age, sal> Clustered B+ tree file, Alterna6ve (1), search key <age, sal> Heap file with unclustered B + tree index on search key <age, sal> Heap file with unclustered hash index on search key <age, sal> Opera6ons to Compare •  •  •  •  •  Scan: Fetch all records from disk Equality search Range selec6on Insert a record Delete a record Assump6ons in Our Analysis •  Heap Files: –  Equality selec6on on key; exactly one match. •  Sorted Files: –  Files compacted aYer dele6ons. •  Indexes:...
View Full Document

Ask a homework question - tutors are online