PracticalDatabaseDesignandTuning.pptVIP

Chapter 16Practical Database Design and Tuning Chapter Outline 1. Physical Database Design in Relational Databases 2. An Overview of Database Tuning in Relational Systems. 1. Physical Database Design in Relational Databases(1) Factors that Influence Physical Database Design Analyzing the database queries and transactions For each query, the following information is needed. The files that will be accessed by the query; The attributes on which any selection conditions for the query are specified; The attributes on which any join conditions or conditions to link multiple tables or objects for the query are specified; The attributes whose values will be retrieved by the query. Note: the attributes listed in items 2 and 3 above are candidates for definition of access structures. Physical Database Design in Relational Databases(2) Factors that Influence Physical Database Design (cont.) Analyzing the database queries and transactions (cont.) For each update transaction or operation, the following information is needed. The files that will be updated; The type of operation on each file (insert, update or delete); The attributes on which selection conditions for a delete or update operation are specified; The attributes whose values will be changed by an update operation. Note: the attributes listed in items 3 above are candidates for definition of access structures. However, the attributes listed in item 4 are candidates for avoiding an access structure. Physical Database Design in Relational Databases(3) Factors that Influence Physical Database Design (cont.) Analyzing the expected frequency of invocation of queries and transactions The expected frequency information, along with the attribute information collected on each query and transaction, is used to compile a cumulative list of expected frequency of use for all the queries and transactions. It is expressed as the expected frequency of using each attribute in each file as a selection attribute or join attrib