一般我们遇到 SQL 性能问题,手段比较有限,诸如分析执行计划 (PEV),改写 SQL,加索引等等,这些也要求一定的经验与功力。 其次作为 DBA,开发也会经常挑战我们,单个 SQL 会消耗多少内存?多少 CPU?不借助额外插件(比如 pg_stat_kcache)的话,我们是无法知晓的。正好最近也一直在捣鼓 SQL 优化相关的事情,今天在学习过程...
(AWR) SQL Tuning Set (STS) SQL Plan Baseline (SPM) Using the EXPLAIN PLAN Command and the DBMS_XPLAN.DISPLAY Function The following examples illustrate how to generate and display an execution plan for our original SQL statement using the different functions provided in the DBMS_...
Thepossible_keys column indicates which indexes MySQL can choose from use to findthe rows in this table. Note that this column is totally independent of theorder of the tables as displayed in the output from EXPLAIN. That means thatsome of the keys in possible_keys might not be usable in ...
These are just basic things for dba’s but very powerful. WE all need them in later stages also. Anil Joshi 19 Aug 15 at 12:54 Thank you for the great info! #9 was tripping me for almost a day (I am sort of new to SQL, but as far as I was concerned the left join x on...
start and stop pumps, take field reading, see and hear equipment running, communicate with the control room, etc. Instructors can mentor and manage training sessions, instead of being tied up in role playing the functions of an Outside Operator from previously provided “remote function” switches...
In business, what are the 3 functions of money? What is business law? What is a business acquisition? What is a business opportunity? What is onboarding in business? What is the business cycle? In business, what does disclosure mean? What is contango in business? What is sole proprietorshi...
What is the main function of the CPU? Describe the role of the beacon frames in 802.11. Describe the strategy of minimal customization. (a) Define confidentiality. (b) Describe how they relate to information security. Describe the importance of recursive functions in procedural programming approach...
Count OVER should allow for DISTINCT, but you're right, it's most likely in there. I rarely use the windows aggregations functions unless I'm doing something incredibly odd, like including multiple aggregations in different patterns off the same dataset and don't want to repull the data. ...
What is the difference between mysql_fetch_object() and mysql_fetch_array() functions in PHP? mysql_... Class hierarchies (I... What is difference between Association, Aggregation and Inheritance relationships? In object oriente... HTML Error Checking... How can I check for HTML errors?
FIGS. 1 through 3, 6 and 10 are schematic block diagrams and flow chart diagrams which illustrate in more detail the preferred embodiments of the present invention. The schematic block diagrams illustrate certain embodiments of modules for performing various functions of the present invention. In gen...