SQL Tuning
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data amount produced by application 2nd 3rd denormalized normalized path to [See data access; execution plans] transferring between applications data access caching and indexes and 2nd 3rd joins and reasons to understand selectivity single-table access paths tables and 2nd 3rd 4th 5th data type conversions, indexes enabled and disabled by 2nd database [See also caching; indexes; tables] adding merged join and filter indexes to adding missing indexes to adding table to, for joins with hidden join filters altering, example of combining tables in for exact one-to-one joins for joins with hidden join filters separating tables in, for one-to-one join to small subset database blocks [See blocks] database vendors SQL tuning and 2nd tools for execution plans provided by 2nd date-type columns in indexes DB2 COALESCE() function execution plans complex controlling displaying 2nd 3rd interpreting multipart nonrobust robust tables for execution-plan data modifying queries with nested views created on the fly null conditions in indexed columns optimization levels type conversions with updating statistics with db2exfmt tool DBMS_STATS package DELETE command deletes in index, performance effects of denormalization in cyclic join graph cases 2nd when to use denormalized data [See also normalized data]2nd detail join ratio 2nd 3rd close to 1.0, affecting optimum execution plan example of in query diagrams large, affecting optimum execution plan 2nd less than 1.0 affecting optimum execution plan caused by query diagram with multiple roots detail table developers, tuning their own SQL diagrams [See query diagrams] directed graph 2nd [See also query diagrams] disconnected query diagrams distributed filters 2nd driving table 2nd choosing 2nd 3rd forcing selection of
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