This paper will optimize the processing of join query based on join index.
文中提出了一种基于数据仓库和位图连接索引的查询方法。
Building bitmap join indexes of dimension tables and fact tables directly may bring a large number of useless index items that affect query efficiency.
直接建立维度表与事实表的位图连接索引会产生大量无用的索引项，影响查询效率。
For the reason of the no order of space data, the algorithm based on join index have to improve for it. The key problem of optimal page-access sequence with a fixed Buffer has been analyzed.
空间数据的无序性，使得应用在其上的利用连接索引的算法需要进一步的改进，为此分析了其中关键的最佳页访问次序问题。
You have a join logical file, but only want the index for the key on SSD, not the secondary indexes.
您有一个连接逻辑文件，但是只希望在SSD中保存键的索引，而不是二级索引。
If there is an index on the join column, the costs will be significantly less; otherwise the database server must perform table scans for all tables, both outer and inner tables.
如果连接列上有一个索引，那么其成本会相当低；否则，数据库服务器就必须对所有表(外部和内部表)执行表扫描。
Also, DB2 cannot use random order index columns as part of a sort merge join.
另外，DB 2无法在排序合并合并连接中使用随机顺序的索引列。
The optimizer will choose dynamic hash join if none of the joined columns has index.
如果连接列上不存在索引，那么优化器将选择动态哈希连接。
You can define guidelines that influence only a few attributes of an execution plan, such as index specification for a certain table in the query or join order for a pair of tables.
可以定义那些只影响执行计划的某些属性的准则，比如查询中的某个表的索引说明，或者一对表的连接顺序。
This is a lot faster than a nested loop join of two table scans without any index usage.
这比不使用任何索引的两个表扫描的嵌套循环连接要快得多。
The number of rows retrieved from the outer table after the database server applies any table filters is small, and the inner table has an index that can be used to perform the join.
在数据库服务器使用所有表筛选器之后，从外部表检索出的行数将很少，而内部表具有一个可用于执行连接的索引。
From the performance perspective, this is considered a very efficient join operation, because the cost for scanning the inner table is optimal via unique access through a unique index.
从性能的角度来看，这被认为是一个非常有效的联接操作，因为通过贯穿唯一索引的唯一访问扫描内部表的成本是最优的。
In this case, the first column of any index, simple or compound, is a candidate to satisfy the star join.
在这种情况下，任何索引的第一行，不管简单或复杂，都是满足星型联接的一个候选者。
Therefore, DB2 can use a DOUBLE index for faster join processing.
因此，DB 2可以使用DOUBLE索引用于快速连接处理。
This join method is usually used when no index is available on the join columns for the joining tables.
当连接表的连接列上没有可用索引时，通常使用该连接方法。
The optimizer will then join that temp table to the fact table using the compound index to quickly locate the rows that satisfy the criteria on the dimension tables.
优化器然后使用复合索引将临时表连接到事实表，来快速定位在维度表中满足条件的行。
To summarize the advice for XML join queries, always cast join predicates to the type of the XML index that should be used.
总结一下关于XML连接查询的建议，通常将连接谓词转换为应使用的xml索引类型。
In addition, DB2 can leverage new query and join operators, as well as new index processing techniques, to provide strong runtime performance for queries involving XML documents.
另外，DB 2可以利用新的查询和联结操作符以及新的索引处理技术，为涉及XML文档的查询提供更好的运行时性能。
The result set from FETCH (3) is ordered by the ID column and joined using a merge join with index I1 for T1 to get final result set.
FETCH(3)的结果集是根据ID字段排序的，并且使用T1的索引I1的合并联接而得到最终的结果集。
As shown in the IXSCAN descriptor in Figure 8, the leading column of the index exploited by optimizer is PRODUCT_NUMBER, which does not provide the order required for merge scan join.
如图8的IXSCAN描述符所示，通过优化器利用的索引的领先列是PRODUCT _ NUMBER，其不为合并扫描联接提供所需的顺序。
He hopes other videographers will join his nonprofit "Bicycle Test" project and create a worldwide insecurity index.
他希望其他录像制作人也能加入这个非营利性的“自行车测试”计划，然后得出一个世界范围内的不安全指数。
The guideline specifies that table SECURITY should be the outer table in the join and the XML index SEC_INDUSTRY should be used to access the SECURITY table.
该准则指定应当将表SECURITY 作为连接中的外表，而XML索引 SEC_INDUSTRY 应当被用于访问 SECURITY 表。
If the XML index is defined as double, you cast the join predicate with xs: double.
如果将xml索引定义为double，则用xs： double转换连接谓词。
The location_id join keys that meet the filter requirements on the Location dimension table are pushed down to the index on the Orders table.
Location维度表中满足过滤条件的 location_id连接键被下推至Orders 表的索引。
If the XML index is defined as VARCHAR, you cast the join predicate with fn: string, and so forth as you see in Table 6.
如果将xml索引定义为VARCHAR，则用fn：string转换连接谓词，如表6所示。
The guideline also specifies that the table CUSTACC should be the inner table of the join and the XML index ACC_CURRENCY should be used to access the CUSTACC table.
准则还指定应当将表CUSTACC作为连接的内表，而xml索引acc_currency应当用于访问custacc表。
In the previous section you learned about one type of access method, index scan (IXSCAN), and one type of join method, nested loop join (NLJOIN).
在之前的部分您已经了解了一种类型的访问方法，即索引扫描(IXSCAN)，和一种类型的联接方法，即嵌套循环联接(NLJOIN)。
A new feature of the query optimizer supports a new type of index scan, called an index self-join path.
查询优化器的一项新特性支持一种新的索引扫描，即索引自连接路径。
In general, a nested loop join with sort composite is favored by the optimizer if the inner index is well-clustered and the inner table is expected to be probed many times.
一般来说，如果内部索引是良好的集群且预测内部表被多次探测，则使用复合排序的嵌套循环联将受到优化器的青睐。
The overall cost depends on whether there is an index on the join columns.
总成本取决于连接列上是否有索引。
When a join is executed that incorporates an index that is selective, any column in the dimension table can be used.
当连接执行时，合并选中的索引，此时维度表中的任何列都可使用。
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