Often heard friends complain about doing database application performance problems, such as very low concurrency, response time is collapse, long lock wait, lock upgrades, or even deadlock, and so on. In the process of solving these problems, DBA application developers often find the database "misuse." Include too much unnecessary data returns, unnecessary and inappropriate to lock in the isolation level of abuse and misuse of the stored procedures and so on. However, with the vast database of knowledge required to fully grasp the application developers are really boring difficult. Therefore, I specially refined for application developers to help write some SQL to look forward to help database developers .
"According to our experience (by many industry experts show), In SQL Server to achieve the performance increase of 80% of the Improvement on SQL coding , not Lai Zi Yu Duiyupeizhi Huo Ji Tong performance of Tiaozheng."
- Kevin Kline, etc., Transact-SQL Programming of
"Experience has shown that 80% -90% of the performance tuning was done at the application level rather than at the database level"
- Thomas White Point, Expert One on One: Oracle of
This article will discuss the optimization-based syntax and simple simple query. Grammar-based optimization refers to not consider any of the non-grammatical factors (eg, index, table size and storage, etc.), just consider the SQL statements for the choice of words and writing the order.
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