lec12 - Basics of Physical DB Design Material drawn from...

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1 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 1 Basics of Physical DB Design Material drawn from Chapter 8 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 2 Physical Database Design Logical database design: Choose a schema (I.e., a set of relational tables and views) Physical database design: Choosing how to actually store the tables Goal: Make important queries run faster! Important choices: Which indexes to build? Should we construct materialized views? If running a parallel DBMS, how to partition the data?
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2 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 3 Agenda Basic overview of storage and DBMS architecture Basic overview of indexing Index selection guidelines More after spring break! 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 4 Storage Basics Data’s main home is on secondary storage (“disk”) Needs to persist across program executions Primary storage (“memory”) used as a cache Stores copies of data from disk Tertiary Storage (Tape) Secondary Storage (Magnetic Disk) RAM CPU Cache CPU Primary Storage Typical Storage Hierarchy
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3 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 5 Storage Basics In order for the DBMS to use it, data must be fetched from disk into memory Basic unit of transfer called a page Much more costly to fetch a page from disk than to read a page that is already in RAM! But database often too big to store in memory… Buffer manager is the DBMS software component in charge of moving data back and forth to disk into memory cache ( buffer pool ) 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 6 How is DB stored on disk? Basic abstraction: File of records Each table stored in a file File contains a collection of pages Each page contains one or more records Each record has a record ID (RID) , which is sufficient to locate the record on disk E.g., RID = (Page#, location on page)
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4 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre
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This note was uploaded on 12/08/2011 for the course EECS 484 taught by Professor Staff during the Winter '08 term at University of Michigan.

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lec12 - Basics of Physical DB Design Material drawn from...

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