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If Your Version is 11.5 or 11.9.x

See the section New Unix File System Device Support in Chapter 6 of this

manual. See also the sections on

disk init and sp_deviceattr in the Reference

Manual at http://manuals.sybase.com:80/onlinebooks/group-

as/asg1250e/refman/@Generic__BookView

for more information.

12.0 Query Processing Changes

The query processing and optimizer changes introduced in ASE 12.0 are less

extensive than those in 11.9.2, and should provide improved performance for

most sites. These changes include the following:

• Predicate Transformation and Factoring

• 50 Tables in a Query

• Abstract Query Plans

• Increased Optimization Time

• Like Optimization Enhancements

For information on optimizer changes over recent ASE releases, see also the

collection

An Introduction to Sybase Adaptive Server Enterprise’s Modern

Optimizer at http://my.sybase.com/detail?id=1013556

. This downloadable

collection of optimizer-related articles published in the ISUG Technical

Journal requires Acrobat Reader.

Predicate Transformation and Factoring

Predicate Factoring provides significant performance improvement in queries

with limited access paths, that is, very few possible SARGs, Joins, or

or clauses

that can be used to qualify rows in a table.

Additional optimization is achieved by generating new search paths based on

join conditions, search clauses, and optimizable

or clauses.

Predicate factoring helps query optimization by extracting optimizable clauses

from predicates linked with or (difficult to optimize) and replacing them with

and clauses (easier to optimize) thus providing the optimizer with more usable

SARGs. The more SARGs available, the more information the optimizer has

and the more likely it is to chose an efficient plan.

Full cartesian joins are avoided for some complex queries.

Example:

1 2 ... 55 56 57 58 59 60 61 62 63 64 65 ... 145 146

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