View merging is not possible for a view that has multiple base tables if it is on the right side of an outer join. If a view on the right side of an outer join has only one base table, however, the optimizer can use complex view merging even if an expression in the view can retur...
View merging is not possible for a view that has multiple base tables if it is on the right side of an outer join. If a view on the right side of an outer join has only one base table, however, the optimizer can use complex view merging even if an expression in the view can retur...
对于不同驱动表时,执行计划如下:(由于OMem、1Mem根据上次sql执行估算出来的,所以每个sql多执行几次,去最后一次结果) select/*+ leading(t)*/count(*)fromt,ttwheret.col=tt.colselectcount(*)fromt,ttwheret.col=tt.colPlanhash value:3743140366Planhash value:1389617266--- ---...
View merging is not possible for a view that has multiple base tables if it is on the right side of an outer join. If a view on the right side of an outer join has only one base table, however, the optimizer can use complex view merging even if an expression in the view can retur...
The index in the hint is the primary key index, defined as (client_id, product_id, id) and, as you can see, the query specifies exactly those three column with equality predicates – albeit with an “in-list” for the final column of the index. You’ll also notice that the table ...
Description: The BATCH_TABLE_ACCESS_BY_ROWID hint instructs the optimizer not use batch table access by rowid. SQL?? HelloDBA.com> alter session set "_optimizer_batch_table_access_by_rowid"=true; HelloDBA.com> exec sql_explain('select /*+NO_BATCH_TABLE_ACCESS_BY_ROWID(o)*/* from t...
USE_HASH_GBY_FOR_PUSHDOWN(@"MAIN") END_OUTLINE_DATA */ You’ll notice in the Outline Data that Oracle has recorded the use_hash_gby_for_pushdown() hint and the gby_pushdown() hint. I’ll be repeating the query disabling each of these hints in turn – which is why the negative ...
2)) b ON b.menu_id = a.menu_id LEFT JOIN TABLE(tf_merge_auth_func_user(1001, 12, 1)) c ON c.menu_id = a.menu_id; 执行计划 --- 分享回复赞 vb吧 梦幻般的金面具 利用SQLT 诊断和优化问题SQL优化SQL是个比较费力的技术活,不停的分析执行计划,加hint,加索引,分析统计信息等等。别担心...
where dept.deptno=emp.deptno;DEPTNO---302010 大体说了下关于半连接的一些实现,可能在实际的使用中,最直观的感受还是通过执行计划来看到。 启用了半连接,在执行计划中会有semi的字样。 也可以手动指定不需要走半连接。使用Hint no_semijoin
q As a last resort, use a hint to change the plan (if you know what kind of plan you want). For additional SQL tuning suggestions, please consult: q Oracle Performance Tuning Guide, SQL Tuning Overview q Document 390374.1: Oracle Performance Diagnostic Guide, Query Tuning Oracle Database ...