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Oracle中Hint深入理解(五)
2015-11-21 02:07:02 来源: 作者: 【 】 浏览:5
Tags:Oracle Hint 深入 理解
able scan for the specified table. The syntax of the FULL hint is FULL(table) where table specifies the alias of the table (or table name if alias does not exist) on which the full table scan is to be performed.
ROWID The ROWID hint explicitly chooses a table scan by ROWID for the specified table. The syntax of the ROWID hint is ROWID(table) where table specifies the name or alias of the table on which the table access by ROWID is to be performed. (This hint depricated in Oracle 10g)
CLUSTER The CLUSTER hint explicitly chooses a cluster scan to access the specified table. The syntax of the CLUSTER hint is CLUSTER(table) where table specifies the name or alias of the table to be accessed by a cluster scan.
HASH The HASH hint explicitly chooses a hash scan to access the specified table. The syntax of the HASH hint is HASH(table) where table specifies the name or alias of the table to be accessed by a hash scan.
HASH_AJ The HASH_AJ hint transforms a NOT IN subquery into a hash anti-join to access the specified table. The syntax of the HASH_AJ hint is HASH_AJ(table) where table specifies the name or alias of the table to be accessed.(depricated in Oracle 10g)
INDEX The INDEX hint explicitly chooses an index scan for the specified table. The syntax of the INDEX hint is INDEX(table index) where:table specifies the name or alias of the table associated with the index to be scanned and index specifies an index on which an index scan is to be performed. This hint may optionally specify one or more indexes:
NO_INDEX The NO_INDEX hint explicitly disallows a set of indexes for the specified table. The syntax of the NO_INDEX hint is NO_INDEX(table index)
INDEX_ASC The INDEX_ASC hint explicitly chooses an index scan for the specified table. If the statement uses an index range scan, Oracle scans the index entries in ascending order of their indexed values.
INDEX_COMBINE If no indexes are given as arguments for the INDEX_COMBINE hint, the optimizer will use on the table whatever boolean combination of bitmap indexes has the best cost estimate. If certain indexes are given as arguments, the optimizer will try to use some boolean combination of those particular bitmap indexes. The syntax of INDEX_COMBINE is INDEX_COMBINE(table index).
INDEX_JOIN Explicitly instructs the optimizer to use an index join as an access path. For the hint to have a positive effect, a sufficiently small number of indexes must exist that contain all the columns required to resolve the query.
INDEX_DESC The INDEX_DESC hint explicitly chooses an index scan for the specified table. If the statement uses an index range scan, Oracle scans the index entries in descending order of their indexed values.
INDEX_FFS This hint causes a fast full index scan to be performed rather than a full table.
NO_INDEX_FFS Do not use fast full index scan (from Oracle 10g)
INDEX_SS Exclude range scan from query plan (from Oracle 10g)
INDEX_SS_ASC Exclude range scan from query plan (from Oracle 10g)
INDEX_SS_DESC Exclude range scan from query plan (from Oracle 10g)
NO_INDEX_SS The NO_INDEX_SS hint causes the optimizer to exclude a skip scan of the specified indexes on the specified table. (from Oracle 10g)

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Hints for Query Transformations

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NO_QUERY_TRANSFORMATION Prevents the optimizer performing query transformations. (from Oracle 10g)
USE_CONCAT The USE_CONCAT hint forces combined OR conditions in the WHERE clause of a query to be transformed into a compound query using the UNION ALL set operator. Normally, th
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