db2 sql performance tuning

thickness of the arrow lines indicates the amount of data. In a graphical execution plan, each of the different operators has its own property values, and we can move the mouse over the operator icon to view Of course, you can also right-click on the icon, view the properties, go to the Properties panel and view more detailed property values The detailed indicator values for each operator in this case are described later, but there are a few key values here, which can be said to mention a lit

DB2 tuning SQL Execution Analysis I have always had a misunderstanding that it is the same to not creating indexes for all the fields in the table. Therefore, when the data volume reaches 1 million in a practical application, the retrieval speed is obviously slow, and the CPU usage during query execution is very high, which affects other jobs and leads to chain r

I. Preface Index plays an important role in database performance. The advantages and disadvantages of index design directly affect the efficiency of DB execution. Therefore, when performing DB tuning, some of them will start to process the index. SQL server also provides a good tool for Database Engine Tuning Advisor a

In the DB2 tuning process, you often want to be able to get SQL that is slow to execute in your current production environment, which you can then fine tune for specific slow SQL. The following scripts can be exploited, or are cumbersome to operate, and need to be run manually.DB2 Connect to Tablename;

weeks data in tens of millions of.Lan Hua Main 16:13:22Ok.Orchid Island Main 16:16:29So change the SQL:with T1 as (Select count (t.c1), t.c1,t.c2,t.c3,t.c4,t.c5From Tab1 twhere T.c2 not in (' Val1 ', ' val2 ', ' val3 ', ' val4 ', ' VAL5 ')and C1 is not NULLGroup by T.C1, T.C2,T.C3,T.C4,T.C5)Select T1.c1,t1.c2,t1.c3,t1.c4,t1.c5from T1Where NOT EXISTS (Select/*+ Use_hash (m,n) */M.C1, M.C2,M.C3,M.C4,M.C5from T1 m,tab2 Nwhere N.c2 > Sysdate-14and m.c1 = N.c1and t1.c2 = M.C2);Orchid Island Main 16:

can avoid Key lookup is perfect, let's revise non-clustered index to include it in the index with the Include keyword His fields are:[SQL] DROP INDEX idx_non_clust_salesorddetaildemo_modifieddate on salesorddetaildemo GO CREATE nonclustered INDEX idx_non_clust_salesorddetaildemo_modifieddate on salesorddetaildemo (ModifiedDate) INCLUDE ( ProductID, UnitPrice ) GO --Clear the cache, only for the development environment! DB

both are created in the SGA but SQL plan directives have not yet been persisted to the Sysaux table space, and statistical feedback is used during the re-optimization period, ignoring the existence of SQL plan directives.Ø both are created but the SQL plan directives are persisted to the Sysaux table space, and the SQL