sql tuning tutorial

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

In the case of performance problems with Oracle databases, it is less effort to use Oracle's own toolkit to give reasonable tuning recommendations.Tuning Advisor is optimized for the execution plan of the input SQL setThe Accsee Advisor is a recommendation on how much performance is improved if SQL set is introduced into an index or partition at this moment.SQL

Database Tuning tutorial (5) Roles of indexes and types of indexes, tuning IndexesIii. Index In the previous chapter, we learned how to use explain to generate a query execution plan (QEP), so as to discover problems with the statement. Three results returned by explain are related to the index (possible key, key, and extra). It can be seen that the index plays

Tags: upd alt has meaning tab logic for good problem useObjective In the previous article we analyzed the role of statistical information in the database, and we have learned how the database uses statistics to control the distribution of the contents of tables in the database. Children's shoes are not clear and can be clicked for reference. As a tuning series of articles, the index of the database is certainly not less, so this article we began to an

ObjectiveIn the previous article we analyzed the role of statistical information in the database, and we have learned how the database uses statistics to control the distribution of the contents of tables in the database. Children's shoes are not clear and can be clicked for reference.As a tuning series of articles, the index of the database is certainly not less, so this article we began to analyze this piece of content, about the basic knowledge of

turned on, the default setting for this parameter is false, which means that the SQL plan Baselines is not actively captured by itself. However, the DBA sets it to TRUE,SPM at the session or system level to start recording the operation of the SQL statement. When an SQL statement is run more than once. The SQL stateme

Tags: Star ref note + + limit base min ant into1, Preface: SQL Tuning has been the DBA of the more laborious technology, and many DBAs if not engaged in the development of the work, then tuning is a headache work, even if the SQL tuning is a strong master, in the process of

Oracle 10 Gb later optimizer supports two modes: Normal Mode and tuning mode. In most cases, the optimizer is in normal mode. The CBO-based Normal Mode only takes into account a small part of the Execution Plan set to select which execution plan, because it needs to be as short as possible, it is usually several seconds or milliseconds to parse the current SQL statement and generate an execution plan. There

| | 471 | 43803 | 979 (1) | 00:00:12 ||* 3 | TABLE ACCESS Full | T1 | 471 | 39564 | 36 (0) | 00:00:01 ||* 4 | INDEX RANGE SCAN | T1_idx | 1 | | 1 (0) | 00:00:01 |--------------------------------------------------------------------------------------predicate information (identified by Operation ID):---------------------------------------------------3-filter ("A". ") object_name "like '%t1% ')4-access ("A". ") object_id "=" B "." OBJECT_ID ")Note------SQL