Sql Statements are used to retrieve data from the database. We can get same results by writing different sql queries. But use of the best query is important when performance is considered. So you need to sql query tuning based on the requirement. Here is the list of queries which we use...
Whenever the query optimizer is unable to automatically generate an efficient execution plan, some manual tuning is required. For that purpose, Oracle provides several techniques. Table 7鈥 1 summarizes them. The goal of this chapter is not only to describe these techniques in detail but also to...
If we want to succeed in SQL Server query tuning, we should have sufficient knowledge about some tools.STATISTICS IOreport is one of the major tools, that helps to find out the disk activity statistics of the executed queries. When we enable this option, it displays the statistical disk acti...
This method is thoroughly described in the book SQL Tuning: Generating Optimal Execution Plans by Dan Tow.In real life, the query optimizer chooses the optimal order to join tables automatically. You can make it follow the predesigned order with the OPTION (FORCE ORDER) query hint, which we’...
In this presentation I'll show you how to use hints, indexed views, plan guides, and the query store to solve some not so common performance problems. Plus we'll look at a bonus trick for when you have many tenants with wildly varying amounts of data. I'll also show examples of prob...
The guidelines described in this section are oriented to production SQL that will be executed frequently. Most of the techniques that are discouraged here can legitimately be employed in ad hoc statements or in applications run infrequently where performance is not critical. ...
(6)Adaptive optimization and self-tuning techniques 使用自调优技术来简化系统管理的任务,并减轻estimation误差的影响,这本身就产生了调优和验证方面的挑战。例如,SQLServer的自动更新统计数据的策略对于某些客户场景可能过早发生,导致不必要的CPU和I/O消耗,而对于其他场景,它可能过晚发生,导致代价评估不准想。一些能够...
Database tuning overlaps with query tuning; so, good indexing and avoiding improper queries help in increasing the database efficiency. In addition, increasing storage, updating to latest database versions and investing in a more powerful CPU (if needed) are also some of the general techniques....
Oracle 12c offers a useful utility called the SQL Tuning Advisor. You can use this built-in tool to provide suggestions or recommendations about certain SQL statements. Although it may not always give perfect advice, just like anything else, having it in your toolbox of tuning techniques is be...
Creating covering indexes for the most frequently executed queries is one of the easiest and most common techniques used in query tuning. It works particularly well in situations where the table contains a number of columns but only a few of them are frequently referenced by queries. By creating...