Tuning in Relational Systems 2012/06/04

Index The performance of queries largely depends upon what indexes or hashing scheme exist. – Efficiency of queries – Maintain overload

Tuning in Relational Systems As a DBA (database administrator), you have to know: – The files that are accessed by queries. – The attributes on which selection conditions are specified. – Expected frequency of invocation of query and transaction. – Time constraints of queries and transaction.

Tuning in Relational Systems As a DBA, you have to decide: – Indexing – Denormalization Tuning in Relational Systems – Tuning indexes – Tuning the database design – Tuning queries

Tuning Indexes Certain queries may take too long to run for lack of indexes. Certain indexes may not get utilized at all. Certain indexes may be causing excessive overhead because the index is on an attribute that undergoes frequent changes.

Tuning the Database Design Existing tables may be joined because certain attributes from two or more tables are frequently needed together. For the given set of tables, there may be alternative design choices, all of which achieves 3NF or BCNF.

Tuning Queries A query issues too many disk access. The query plan shows that relevant indexes are not being used.