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How the optimizer analyzes a query sybase? The optimizer sql server examines each clause of the query and determines if it can be useful in limiting the amount of data that must be traversed, ie, if the clause is useful as search argument (SARG) or as part of the criteria for marriage . A clause used as a search argument is referred to as sargable or optimizable and can make use of an index for faster recovery. A SARG limits a search because it specifies an exact match, a range of values or a combination of two or more items joined by AND logic function. The use of clause SARG may use an index for more rapid recovery of information. However, an expression that is not sargable can not limit the search, so an index is not useful for these expressions so does the sybase? |
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Have a look at this section in the documentation on "How the optimizer works" Ok.thanks.
(29 Jan '13, 21:01)
Walmir Taques
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