If this hint specifies no indexes, then the optimizer does not consider a scan on any index on the table. This behavior is the same as a NO_INDEX hint that specifies See Also: Oracle Database SQL Language Reference for syntax and a more detailed Therefore, even though you gave the INDEX hint, the optimizer might not use NO_INDEX hint. http://docs.oracle.com/cd/B19306_01/server.102/b14200/ sql_elements006.htm#BABHJBIB. for instance. SELECT /*+ Jul 11, 2011 no_index hint oracle 10g not working. In Oracle Database, hints are directives that must be obeyed (with a couple of minor exceptions that Oracle does not report when a hint is mis-spelled and because hints are hint will be ignored because the table name is not specified in the index hint:. Specifying an index hint on a table that has no indexes. Specifying a parallel hint for an index range scan. You need to be especially careful with validation of hints
If you specify hints incorrectly, then Oracle ignores them but does not return an error. Therefore, even though you gave the INDEX hint, the optimizer might not
If this hint specifies no indexes, then the optimizer considers the cost of a scan on each available index on the table and then performs the index scan with the lowest cost. The optimizer can also choose to scan multiple indexes and merge the results, if such an access path has the lowest cost. The no_index hint is most commonly used in cases where you have determined that a parallel full-table scan will outperform an index range scan. The no_index hint is equivalent to the full hint and is rarely used in SQL tuning. A root cause solution to using the no_index hint is to re-analyze the schema objects and for the optimizer not to use an index without the need for the no_index hint. NO_INDEX hint does not work unless you specify Table name (or alias name if used in the query) after "NO_INDEX(" and before the index name. for example, /*+ NO_INDEX(TAB1 INDEX_TAB1_C1) Once you put this, the hint will start working, Make sure if you have used alias then use alias name here. It says “The NO_INDEX hint does not applying to UNIQUE indexes. The NO_INDEX hint applies to function-based, B*-tree, bitmap, cluster, or domain indexes.” I have tested it on 9.2.0.8, 10.2.0.3 and 11.2.0.1 and I see that “no_index hint” WORKS as intended even on unique indexes. This means that the default Oracle optimization that doesn't use an optimizer hint will try to find the string inside the indexed field first and also find if the data it is a sub-string of the data in the field, then it will check that the data doesn't match another specific string. After the index is checked the other columns are then checked. Index hints are not needed as often with the newer Oracle databases. You should test your code in Oracle10+ using no hints at all. Main index hints? The index hint can be used to specify the use of particular indexes. The main index hints include: /*+INDEX(Index name)*/ /*+INDEX_JOIN(emp index1, index2)*/ Forces an index join where two or more indexed columns can be joined using single-column indexes; this can be useful to solve query columns
If this hint specifies no indexes, then the optimizer does not consider a scan on any index on the table. This behavior is the same as a NO_INDEX hint that specifies
The alternative syntax IGNORE INDEX ( index_list ) tells MySQL to not use some If an index hint includes no FOR clause, the scope of the hint is to apply to all The following table highlights Oracle hints based on Oracle hints optimization: Category. Hint. Available For. Notes. ACC PATH. AND_EQUAL. /*+ CLUSTER If no indexspec is supplied, the optimizer will try to scan with each avail index.
If no indexes are given as arguments for the INDEX_COMBINE hint, the optimizer uses whatever Boolean combination of bitmap indexes has the best cost estimate for the table. If certain indexes are given as arguments, the optimizer tries to use some Boolean combination of those particular bitmap indexes.
It says “The NO_INDEX hint does not applying to UNIQUE indexes. The NO_INDEX hint applies to function-based, B*-tree, bitmap, cluster, or domain indexes.” I have tested it on 9.2.0.8, 10.2.0.3 and 11.2.0.1 and I see that “no_index hint” WORKS as intended even on unique indexes. This means that the default Oracle optimization that doesn't use an optimizer hint will try to find the string inside the indexed field first and also find if the data it is a sub-string of the data in the field, then it will check that the data doesn't match another specific string. After the index is checked the other columns are then checked.
Feb 16, 2010 The Oracle hint have to append after the 'select', not before. Hibernate generated query /* + INDEX(stock idx_stock_code) */ select. Copy.
Feb 25, 2016 Then no parallelism will be used. I tried using hints like FULL(t) to force an index create to use a full table scan instead of an existing index – but At least one of the tables is accessed through a full table scan, or an index is accessed Oracle checks the statement for a parallel hint. The intent is to get four SQL*Loader sessions going at once, not to run four sessions one at a time. Why are Optimizer hints ignored? ▫ Specifying an index hint on a table with no indexes. Invalid hint. Invalid hint because no indexes. Oct 11, 2018 Add a first row hint, that way oracle may respond the same way as to the datagrip query. CREATE TABLE DUMMY_SCHEMA.DUMMY_TABLE Feb 16, 2010 The Oracle hint have to append after the 'select', not before. Hibernate generated query /* + INDEX(stock idx_stock_code) */ select. Copy. Purpose: NO_INDEX hint explicitly notifies the optimizer to not to use the specified index(s). This can be used for query testing purpose without dropping the actual index. This can be used for query testing purpose without dropping the actual index.