G heap le aribute name and type for each aribute index

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: Systems 3ed , R. Ramakrishnan and J. Gehrke 24 System Catalogs (will revisit in DavisDB, Part 3) •  For each index: –  structure (e.g., B+ ­tree) and search key fields •  For each rela6on –  name, file name, file structure (e.g., heap file) –  a[ribute name and type, for each a[ribute –  index name, for each index –  integrity constraints •  For each view: –  view name and defini6on •  Plus sta6s6cs, authoriza6on, buffer pool size, etc –  Catalogs are themselves stored as rela1ons! AEtr_Cat(aSystem matalog Table ,for pe, position) t xample: ttr_na C e, rel_name ty A[ributes attr_name attr_name rel_name type position sid name login age gpa fid fname sal rel_name Attribute_Cat Attribute_Cat Attribute_Cat Attribute_Cat Students Students Students Students Students Faculty Faculty Faculty type string string string integer string string string integer real string string real abase Management Systems 3ed , R. Ramakrishnan and J. Gehrke position 1 2 3 4 1 2 3 4 5 1 2 3 26 Summary •  Disks provide cheap, non ­vola6le, but slow storage –  Random access, but cost depends on loca6on of page on disk; important to arrange data sequen6ally to minimize seek delays •  DavisDB isn't very smart about this •  Buffer manager brings pages into RAM –  Page stays in RAM un6l released by requestor –  Wri[en to disk when frame chosen for replacement (which is some 6me ajer requestor releases the page) –  Choice of frame to replace based on replacement policy –  Tries to pre ­fetch several pages at a 6me •  DavisDB doesn't worry about this Summary (Con6nued) •  File layer keeps track of pages in a file, and supports abstrac6on of a collec6on of records. –  Pages with free space iden6fied using linked list or directory structure (similar to how pages in file are kept track of) •  Indexes support efficient retrieval of records based on the values in some fields •  Catalog rela6ons store informa6on about rela6ons, indices, and views. (Informa1on that is common to all records in a given collec1on.) File and Buffer Management in DavisDB...
View Full Document

This document was uploaded on 03/12/2014 for the course CSCI 165B at UC Davis.

Ask a homework question - tutors are online