28 Oct 2013 Here is a complete list of Hints use for the DBA Oracle; Hint for access by FTS, index scan, ordered, by RoWID

If more than one index is provided, the indexes are separated by at least one space; the INDEX_COMBINE hint is recommended for this use case though. ss. Oracle Tips by Burleson. Using CTAS with an Index Hint The CTAS with an index hint executes quite differently than CTAS with order by. 表明對表選擇索引的掃瞄方法. 例如: SELECT /*+INDEX(BSEMPMS SEX_INDEX) USE SEX_INDEX BECAUSE THERE ARE FEWMALE BSEMPMS */ FROM  For a hint on a combination of multiple indexes, Oracle recommends using INDEX_COMBINE rather than INDEX , because it is a more versatile hint. If the INDEX  11 Nov 2008 “If you want the optimizer to take the invisible index into account, you must use the index hint, as shown in the following example:“. Oracle  28 Oct 2013 Here is a complete list of Hints use for the DBA Oracle; Hint for access by FTS, index scan, ordered, by RoWID

28 Nov 2012 Hints are CBO directives. If Oracle can use the hint, it will only produce explain plans that contain the hint directive. This article examines index 

there are no problems with hints. if hints were a problem, then oracle wouldn't allow them however, if you drop the index and recreate it with a different name, then the hint becomes a comment and by using a hint, you're saying that you know better than the optimizer. not saying that you don't (I don't know you), but it is a bold statement. and if the amounts of data change over time (rows per Using INDEX Hints. When you specify an INDEX Hint, the optimizer knows that it has to use the INDEX specified in the hint. In this case, the optimizer does not go for a Full Table Scan nor does it use any other index. In addition, it does not calculate the cost of the Index to be used. The CBO will do what the CBO wants to do, and if it does not want to use a hint it will not use the hint even if you make the hint nicely. There are some things you can to to influence the CBO to use a hint though. Index hints can also be placed inside subqueries. Oracle provides the index hint, the and_equal hint, the index_asc hint, the index_combine hint, the index_desc hint, and the index_ffs hint to redirect the optimizer's use of indexes to access table rows. Let’s begin our discussion with the most common hint, the index hint. The Index Hint If you force the use of the index with an hint, Oracle will do a full index scan. It will not be interesting for you.If your query has a sense, maybe your data model is not appropriate. Maybe a good way is to split you column nr_certificate in two columns. If it's possible, it will be easy to you after to have the good and quick query. What is the trick in Oracle force index? Answer: Given accurate CBO statistics, the Oracle optimizer will also choose the "best" index, and it's not always a good idea to force a specific index unless you are sure that the index will always be the fastest path to your rows. The easiest way to force index usage is with the index hint. You can prevent the use of an index on a column without hints by applying a function to it. You'll want to use a "no-op" function so the column values aren't changed. For numbers this could be adding zero, for strings appending the empty string: select * from t1,t2 where t1.id || '' =t2.id;

The USE_NL hint causes Oracle to join each specified table to another row source with a nested loops join using the specified table as the inner table. The syntax of the USE_NL hint is USE_NL(table table) where table is the name or alias of a table to be used as the inner table of a nested loops join.

Use of the USE_NL and USE_MERGE hints is recommended with the ORDERED hint. Oracle uses these hints when the referenced table is forced to be the inner table of a join; the hints are ignored if the referenced table is the outer table. there are no problems with hints. if hints were a problem, then oracle wouldn't allow them however, if you drop the index and recreate it with a different name, then the hint becomes a comment and by using a hint, you're saying that you know better than the optimizer. not saying that you don't (I don't know you), but it is a bold statement. and if the amounts of data change over time (rows per Using INDEX Hints. When you specify an INDEX Hint, the optimizer knows that it has to use the INDEX specified in the hint. In this case, the optimizer does not go for a Full Table Scan nor does it use any other index. In addition, it does not calculate the cost of the Index to be used.

For access path hints, Oracle ignores the hint if you specify the SAMPLE option the INDEX hint, the optimizer might not necessarily use that hint, because the 

11 Nov 2008 “If you want the optimizer to take the invisible index into account, you must use the index hint, as shown in the following example:“. Oracle  28 Oct 2013 Here is a complete list of Hints use for the DBA Oracle; Hint for access by FTS, index scan, ordered, by RoWID 23 Nov 2010 Due some reasons it performs an “INDEX SKIP SCAN” on index You can also easily hint complex queries by using the whole outline data of 

2011年9月6日 在SQL語句優化過程中，我們經常會用到hint,現總結一下在SQL優化過程中常見 Oracle hint的用法： 如果是要指定使用某個Index,則利用規則。 1.

The index hint is the key here, but the more up to date way of specifying it is with the column naming method rather than the index naming method  28 Nov 2012 Hints are CBO directives. If Oracle can use the hint, it will only produce explain plans that contain the hint directive. This article examines index  2013年8月19日 Oracle的優化器(Optimizer)有兩種優化方式, Hint也不例外，除了/*+rule*/ 例如: SELECT /*+ INDEX(BSEMPMS SEX_INDEX) USE SEX_INDEX  Index Hints. Oracle Tips by Burleson Consulting. While we will investigate tuning with indexes in detail in Chapter 20, let's make a quick review of using  In various SQL implementations, a hint is an addition to the SQL standard that instructs the database engine on how to execute the query. For example, a hint may tell the engine to use or not to use an index (even if Oracle implements hints by using specially-crafted comments in the query that begin with a + symbol, thus  For access path hints, Oracle ignores the hint if you specify the SAMPLE option the INDEX hint, the optimizer might not necessarily use that hint, because the 

select /*+ index(customer cust_primary_key_idx) */ * from customer; Also note that of you alias the table, you must use the alias in the index hint: select /*+  2011年9月6日 在SQL語句優化過程中，我們經常會用到hint,現總結一下在SQL優化過程中常見 Oracle hint的用法： 如果是要指定使用某個Index,則利用規則。 1. You can use the INDEX hint for domain, B-tree, bitmap, and bitmap join indexes. However, Oracle recommends using INDEX_COMBINE rather than INDEX for the   The index hint is the key here, but the more up to date way of specifying it is with the column naming method rather than the index naming method  28 Nov 2012 Hints are CBO directives. If Oracle can use the hint, it will only produce explain plans that contain the hint directive. This article examines index