Titlebook: SQL Server 2008 Query Performance Tuning Distilled; Grant Fritchey,Sajal Dam Book 2009 Sajal Dam and Grant Fritchey 2009 Microsoft SQL Ser

察觉

Bookmark Lookup Analysis,ith nonclustered indexes is the cost of excessive key lookups, commonly known as ., which are a mechanism to navigate from a nonclustered index row to the corresponding data row in the clustered index or the base table. Therefore, it makes sense to look at the cause of bookmark lookups and to evaluate how to avoid this cost.

松驰

Fragmentation Analysis,clustered) on a table, the cost of data retrieval is reduced by properly ordering the leaf pages of the index and the rows within the leaf pages. In an OLTP database, data changes continually, causing fragmentation of the indexes. As a result, the number of reads required to return the same number of rows increases over time.

狂怒

土产

笨重

formula

978-1-4302-1902-6Sajal Dam and Grant Fritchey 2009

放逐某人

indifferent

minimum-distance solution. This is where the similarities end, however, because there aren’t any tricks for finding perfect solutions to the TSP. The problem is NP-hard [135]: there are no known algorithms for finding perfect solutions that have a complexity that grows as only a polynomial function

报复

iterations of random variation and selection. Random variation provides the mechanism for discovering new solutions. Selection determines which solutions to maintain as a basis for further exploration. Metaphorically, the search is conducted on a landscape of hills and valleys (see figure 7.1), whi

Parabola

iterations of random variation and selection. Random variation provides the mechanism for discovering new solutions. Selection determines which solutions to maintain as a basis for further exploration. Metaphorically, the search is conducted on a landscape of hills and valleys (see figure 7.1), whi