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介绍只包含表连接而没有聚合的物化视图。与聚合类似，表连接也是相当消耗资源的操作， 将其结果预先计算并存储于物化视图中，可以提高SQL执行效率。 每一个基表(包括inline view)的Rowid必须出现在物化视图的select部分。这也是该物化视图可以快速刷新的必要条件之一。其他条件包括：From&n...

Prebuilt MV alter table

MV Staleness Query_Rewrite_Integrity nonvalidated rely referential integrity

物化视图 快速刷新 DBMS_MVIEW DBMS_ADVISOR.TUNE_MVIEW explain_rewrite

Oracle Compound Trigger ORA-04091

IntroductionThe server result cache is a memory pool within the shared pool.When a query executes, the database looks in the cache memory to determine whether the result exists in the cache. If the result exists, then the database retrieves the result from memory instead of executing the query....

Oracle Sequence Cache Performance 性能

快速

Oracle Imp Exp data pump

Date Timestamp(6) ORA-00001

Nologging direct-path insert redo

Advanced OLTP Compression

Hybrid Columnar CompressionHybrid Columnar Compression is a feature of the Enterprise Edition of Oracle Database 11g that is dependent on the underlying storage system. Only Exadata storage, ZFS storage, and Pillar Axiom 600 storage support Hybrid Columnar Compression.With Hybrid Columnar Compres...

Basic Compression value repetition

Oracle Timezone systimestamp current_timestamp timestamp with local timezone timestamp with time zone

PARALLEL_DEGREE_POLICY Specifies whether or not automatic degree of Parallelism,statement queuing, and in-memory parallel execution will be enabled. MANUAL is the default, which disables automatic degree of parallelism, statement queuing, and in-memory parallel execution. AUTO enables automati...

Cardinality FeedbackThis blog is an extraction of https://blogs.oracle.com/optimizer/entry/cardinality_feedbackIntroduced in 11gR2. The purpose of this feature is to automatically improve plans for queries that are executed repeatedly.During the first execution of a SQL statement, an executi...

Consider the follow query against SH schema.select /*MY5*/ cust_id, sum(amount_sold) from sales where prod_id=:prod_id group by cust_id;With DBMS_XPLAN.Display_cursor, user is able to retrieve and see execution plan.SELECT t.*FROM v$sql s, table(DBMS_XPLAN.DISPLAY_CURSOR(s.sql_id, s.child_...

SQL Projection is the collective name for the columns that are Selected and returned from a query. In other words, the columns goes behind select in a query. In Oracle, a whole row is first fetched, then data values from the columns within that row are extracted into the known projection.To see th...

Sort join is the first operation of the “SortMerge Join”. Before Oracle joins two row sources, one of the row sources has tobe sorted, which is “sort join”. The name is a bit misleading. All it does is asort on the join key. The “Sort Merge Join” consists of twosteps:...