常见的SQL调优(SQL Tuning)Tips 建立适当的索引(参考《正确建立数据库索引的姿势》) 用UNION替换OR (适用于索引列) 用exist、not exist代替 in、not in 不要以字符格式声明数字(会使索引无效,产生全表扫描) 不要使用select * (在select后列出每一列) 不要JOIN和WHERE子句中进行计算操作(在表中用一新列来事先...
If you’re sure you need SQL tuning, “The fundamental guide to SQL query optimization”offers further insight. It walks you through five performance tuning tips with copy-and-paste queries and case studies, including the one described above. You’ll probably find that the single most important...
While SQL query tuning can be done manually, it’s a complicated and time-consuming process, which is why using SQL tuning tools can allow database administrators to more efficiently maximize the performance of their servers and databases. SQL query performance tuning tools are an essential part ...
SQL (Structured Query LanguageDB2 (DatenbankThe Definitive Solutions-Oriented Guide to IBM(r) DB2(r) for z/OS(r): Now Fully Updated for Both v9 and v10! The largest database tuning performance gains can often be obtained from tuning application code, and applications that use SQL to ...
SDOINDEX table if individual SDO_GIDs will be used as query windows for other Spatial Cartridge layers. Visualizing the indexing tiles, as described inSection A.2.8, can lead to a greater understanding of the tuning process with respect to the size of the tiles. ...
Starting with SQL Server Management Studio v18, the Query Tuning Assistant (QTA) feature guides users through the recommended workflow to keep performance stability during upgrades to newer SQL Server versions, as documented in the section Keep performance stability during the upgrade to ...
I also like to kick of a full database backup after the shrink so that I can maintain the LSN's of the database, this is a must if using Full or Bulk Recovery Mode. Anonymous 2014年9月24日 http://blogs.technet.com/b/sqlpfeil/archive/2012/02/01/four-tips-for-sq...
SQL Tuning: Avoid Correlated SQL Subqueries Acorrelated subqueryis one which uses values from the parent query. This kind of SQL query tends to runrow-by-row, once for each row returned by the outer query, and thus decreases SQL query performance. New SQL developers are often caught structuri...
Diagnose and resolve performance issues and optimize workloads with Foglight for SQL Server performance monitor and tuning tool.
Execution Time 是执行语句的实际时间，不包括 Planning Time。关于 PostgreSQL 的执行计划和性能优化，可以参考 PostgreSQL 官方文档性能提示（https://www.postgresql.org/docs/12/performance-tips.html）。SQLite 执行计划SQLite 也提供了EXPLAIN QUERY PLAN命令，用于获取 SQL 语句的执行计划：sqlite> EXPLAIN QUERY ...