U

Index

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uncorrelated subqueries 2nd
     in classic style or in from clause
     not in ( ), using with
     rewriting as a join in an inline view
     rewriting as inline views in from clause
     sensitivity of operations to data volume increase
     testing for existence without other search criteria
union operator
     querying large quantities of data
unions
     of complex joins
     of intermediate result sets
     overhead of querying large union view
     partitioned tables
uniqueness, enforcement of 2nd
unnecessary coding, avoiding
unpivot operator
update statement, returning ... into ... clause
updates
     against a database
     combining multiple into one
    concurrent
         foreign key indexing
     costly massive updates
     locking and scalability
     making as fast as possible
     multiple massive updates to a table
     optimistic concurrency control
     ranking in terms of overall cost
useless queries
user-defined functions 2nd
users
     not complaining about performance
     number of, concurrency and
     perception of performance improvement