If a representative set of expressions is already stored in the table, the owner of the table can automate the index tuning process by collecting statistics on the expression set, using theDBMS_EXPFIL.GET_EXPRSET_STATSprocedure, and creating the index from these statistics, as shown in the fo...
(case when status in ('STATUS_6','STATUS_7') then null else message_id end) virtual / drop index mt_i1; create index mt_i1 on my_table(rare_status, rare_message_id); execute dbms_stats.gather_table_stats(user,'my_table', method_opt=>'for columns rare_message_id size 1') sel...
Non-bottom-layer indexes should be primary indexes, to make sure that the bottom layer index is in order. Insertion / Deletion performance is even worse than the single-level index. To avoidcascading, we expect every index page to be not full (a dynamic ratio, 50% full for example). Or...
env sys.ODCIEnv) RETURN NUMBER IS stmt VARCHAR2(2000); cnum INTEGER; junk INTEGER; BEGIN stmt := ''; dbms_output.put_line('Exchange Partitions'); -- construct the sql statement stmt := 'alter table ' || ia.IndexSchema || '.' || ia.IndexName || '_sbtree exchange partition '...
Let's delve into the world of indexing and explore how it can turbocharge your SQL queries with a real-time example. Understanding Indexing In simple terms, an index in a database is akin to the index of a book. It allows the database management system (DBMS) to quickly locate specific...
begindbms_auto_index.configure ('AUTO_INDEX_MODE', 'IMPLEMENT');end;/ If you wary of directly implementing the Auto Index feature, using the below example you can create the index but keep it invisible till it is ready for the world. To explain better, the “report_only” feature will ...
exec dbms_auto_index.configure('auto_index_report_retention','31') By default,unusedauto index are dropped after 373 days. Manually created indexes are not dropped by default, but a drop period can be set: six-hundred days in this example: ...
Our image retrieval system, called RELIEF, is implemented on an object-oriented DBMS and is available on the Web. It ensures the management of an image test collection and gives good results, with respect to both execution time and quality of answers. 1 Introduction: Towards Precision-Oriented ...
Audio classification is very important in multimedia retrieval such as audio indexing, analysis and content-based video retrieval. In this paper, we have p... N Sebe,Y Liu,Y Zhuang,... - DBLP 被引量: 13发表: 2007年 Towards evaluation of example-based audio retrieval system using affective...
5.1.1.2Spatial Indexing Example: Virtual Column Partitioning A virtual column is an expression based on one or more existing columns in the base table. While a virtual column is only stored as metadata and does not consume physical space, it can be indexed and also contain optimizer statistics ...