BASIS-11 PERFORMANCE-SQL語法調校

1.SQL語法的效能可以看TX:ST04的shared pool 部份
1.1 SQL area getratio: describe the ratio between matches and request for an object in the libary cache and should be close to 100% for PRD system
1.2 SQL area pinratio : describe the ratio between matches and request for reading and executing objects and should be close to 100% for PRD system
1.3 SQLA.reloads/pin describe the ratio between the necessary reloads (SQL query parsing) and the accesses. 完美值應要接近0
1.4 SQL statement analysis可以找出top sql進而查看explain/abap source..等等
2.若要做單一程式的效能分析亦可用se30去做分析
2.1 用se30去做分析時,要留意同一支程式做第二次分析時,相關效能有可能會變好,原因是相關資料已經load到DB的buffer去了
2.2 st05的sql trace等同於Oracle DB的sql trace,有時亦可搭配此程式做效能分析
3.SAP有提供一些程式最佳效能語法的範本,可從se30或se80進入
4.若因為效能因素需要建index時需留意如下
4.1 標準table,不應任意建index,最好是有note或是原廠發布的文件
4.2 若要建index需在系統不忙的時段,因其亦會耗損效能