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About the or conditions and indexes in mysql 1) myisam table: Mysql> explain select * from a where id = 1 or uid = 2; + ---- + ------------- + ------- + ------------- + --------------- + ------------- + --------- + ------ + --------------------------

Summary of Oracle Performance Tuning recommendationsPrinciple One: Note the connection order in the WHERE clause:Oracle uses a bottom-up sequential parsing where clause, according to which the connection between tables must be written before other

From: http://woainichenxueming.iteye.com/blog/726541I. Optimizing SQL statements in Oracle to improve operational efficiency1. Select the most efficient table name order (valid only in the rule-based optimizer)The Oracle parser processes the table

Experience in SQL statement optimization and SQL statement Optimization (1) select the most efficient table name sequence (only valid in the rule-based seo/'target = '_ blank'> Optimizer ): the ORACLE parser processes the table names in the FROM

MS SQL Server Query optimization methodThere are many reasons for the slow speed of queries, which are common1, no indexes, or no indexes (this is the most common problem with query slowness, is the flaw in programming)2, I/o throughput is small,

SQL statement optimization improves database performance and SQL statement database performance In systems with unsatisfactory performance, apart from the fact that the application load exceeds the server's actual processing capacity, it is more

The performance of the system is not ideal, except in part because the application load does exceed the actual processing capacity of the server, more because the system has a large number of SQL statements need to be optimized. In order to achieve

First, the question of the proposedIn the early stage of application system development, because the database data is relatively small, for querying SQL statements, complex view of writing and so on is not aware of the performance of SQL statements,

Warm tip: This article is from the Internet, I only do a little processing, not detailed research, only as a later unprepared for the need, if you like to enjoy the turn away.First, the question of the proposedIn the early stage of application

See a very comprehensive SQL optimization article, in the development of the work often do not consider the performance of the lack of (at the beginning of the data volume is not seen the difference in speed). But the more you write, the more you