Operating System Support for Database Management

Operating System Support for Database Management Andrew Gladstone CSC 8410 3/26/2007 Background Based on 1981 Stonebraker paper Examine OS services as applicable to database use UNIX used as example OS

INGRES used as example DBMS OS Services Buffer Pool Management File System Scheduling / Process Management Consistency Buffer Management

UNIX provisions: Fixed-size buffer pool Size set upon compilation I/O handled through main-memory cache LRU replacement strategy for misses Block-prefetch for sequential access Deficiencies

Fetch performance Suboptimal replacement strategy Access Types: Sequential access one time Sequential access cyclically re-referenced Random access one time Random access possible rereference

Inefficient prefetch Solutions? DBMS managed buffer pool Composite replacement strategy Database

access in INGRES: Sequential access (no re-reference) : toss immediately Sequential access (cyclical re-reference): MRU Random access (no re-reference): toss immediately Random access (potential re-reference): LRU

Prefetch? Crash Recovery Implemented by the DBMS Intentions List and Commit Flag Requires OS to perform selected force out Critical to ensure accurate post-crash writes / rollbacks

File System Character Arrays Designed for sequential access DBMS data generally not sequential No record management service Two OS trees + one DBMS tree

Why not one tree? Scheduling / Process Mgmt. Two methods proposed Process / user, shared

code / data Single process server Requires DBMS scheduling service Scheduling Challenges

Separate Processes Memory requirements Task switching Relies on OS message-passing system Server Model DBMS

must manage scheduling and m/t Mini OS running in user-space Favored-user class??? Consistency Control OS lock / protection on file - not record level Update order not guaranteed Buffer management / crash-recovery / locking managed by one system

Summary OS provided services too slow or inappropriate Most services provided by DBMS Double-effort results in considerable overhead

Recently Viewed Presentations

  • West Africa

    West Africa

    Most of Africa lands lie within the tropics. Despite this, Africa has diverse vegetation and climate zones as well as many unique physiographic features. Its landscapes range from tropical rainforest to desert and from savanna to snow-capped mountain.
  • Peer to Peer - Strom

    Peer to Peer - Strom

    Peer to Peer David Strom, [email protected] PC Expo/ eBiz presentations June 2001
  • Hierarchies (Trees)  Definition  Data repository in which cases

    Hierarchies (Trees) Definition Data repository in which cases

    * In 1998, Chi et al at PARC introduced the Time Tube A sequence of Disk Trees used to visualize changes in a web site over time This is an example of viewing multiple similar hierarchies Recently, Graham et al...
  • Insert title of presentation Date, name, etc Insert

    Insert title of presentation Date, name, etc Insert

    usask.ca/yoururl. Insert college, presentation title, and/or date as necessary. Agenda item one. Subtitle "Loremipsum dolor sit amet, consecteturadipiscingelit. Proin non mi nunc, utportalibero. Integer leonibh, rutrum a interdum et, faucibusnecenim. Sedconguemalesuadamauris in hendrerit.
  • Chapter 1

    Chapter 1

    Chapter 1 Introducing Public Speaking
  • Agile Methodology and Scrum - Furman University

    Agile Methodology and Scrum - Furman University

    Agile Methodology and Scrum. What is Agile ? Agile proponents believe. Current software development processes are too heavyweight or cumbersome. Too many things are done that are not directly related to software product being produced.
  • Too much of a good thing - d2cax41o7ahm5l.cloudfront.net

    Too much of a good thing - d2cax41o7ahm5l.cloudfront.net

    Trends:'Think of them as epidemics'. Malcolm Gladwell 'The Tipping point' little changes can have big effects; when small numbers of people start behaving differently, that behavior can ripple outward until a critical mass or "tipping point" is reached, changing the...
  • Introduction to Rhetoric and Rhetorical Analysis Through the ...

    Introduction to Rhetoric and Rhetorical Analysis Through the ...

    What is the speaker's attitude towards his subject? Towards his audience? DO NOT confuse tone with mood—mood is the audience side of this coin, while tone is analyzed from the perspective of the author. STYLISTIC DEVICES Stylistic Devices: DIDLS: diction,...