This is the same join predicate applied at FILTER(10).
和应用于FILTER(10) 的连接断言相同。
Query 2 applies the join predicate to the authors table.
查询2对authors表应用连接谓词。
The LIKE predicate can therefore be used as a fuzzy join predicate.
因此,可以使用like谓词作为模糊联结谓词。
In both queries, the join predicate is expressed within the square brackets.
在这两个查询中,方括号中表示了连接谓词。
The following query explicitly casts both sides of the join predicate to DOUBLE.
以下查询明确地将连接谓词的两端转换为DOUBLE。
That is, table CUST_INTEREST could be very selective through the join predicate.
即,通过连接谓词,CUST_INTEREST表的选择性非常强。
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。
When you use the partitioning key in the join predicate, a final consideration needs to be mentioned.
如果在连接谓词中使用分区键(partitioning key),最后还有一点考虑需要顾及。
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。
Generate the expression for the join predicate by applying the join operator to the expressions for the left and right attributes.
将联结操作符应用于左右属性的表达式,从而产生联结谓词的表达式。
Note that the join predicate on the author ID does not contain a literal value that would indicate the data type of the comparison.
请注意,authorID上的连接谓词没有包含文字值,该文字值将表明比较的数据类型。
Therefore, the join cardinality is the product of the cardinalities of two row sets, multiplied by the selectivity of the join predicate.
因此,连接行集数是两个行集的行集数的乘积,被选择的谓词连接的乘积。
Based on guideline (c), you can ignore a separate count query for TBSCAN (4) as the join predicate being resolved is the same as in NLJOIN (2).
按照原则(c),可以忽略tbs CAN(4)的单独count查询,因为解析的连接断言和NLJOIN(2)相同。
As a slightly more sophisticated example, here is a query involving a spatial join, that is, a join where the join predicate is a spatial function.
作为一个稍微复杂些的示例,下面给出一个涉及空间联结(即其中的联结谓词是空间函数的联结)的查询。
TBSCAN (4) — Since this is the same join predicate being resolved at NLJOIN (2), and there are no additional local predicates, we can ignore this operator.
TBSCAN(4)——因为这个连接断言和NLJOIN(2)分析出的相同,并且没有其他局部断言,可以忽略该操作。
When an in predicate (or an equivalent or predicate) is used, the optimizer considers an IN-to-JOIN transformation, converting the in predicate to a join predicate.
当使用了一个in谓词(或一个等价的or谓词)时,优化器将会考虑使用一个in到join的变换,将一个in谓词转换成一个连接谓词。
Since Query 1 expresses the join predicate on the books table, DB2 9.1 and 9.5 perform a table scan on authors and then use the index AUTHORIDX1 to probe into the books table.
由于查询1表达了books表中的连接谓词,所以DB 2 9.1和9.5执行一个扫描authors的表,然后使用索引authoridx 1查找books表。
Start from the leftmost deepest operator, in this case, the OUTER of NLJOIN(2) which is TBSCAN(2), and the INNER which is TBSCAN(4), and then the join predicate itself which is NLJOIN(2).
从最左侧、最深的操作开始,在这里就是NLJOIN(2) 的OUTER即TBSCAN(2),然后INNER 即 TBSCAN(4),最后是连接断言本身即 NLJOIN(2)。
For example, this might happen when two ore more of the tables in the MQT have a referential integrity relationship defined and the join predicate is on their primary key - foreign key columns.
例如,当MQT中的两个或多个表定义了引用完整性关系并且联结谓词在它们自己的主键-外键列上时,就会出现这种情况。
Predicates are reordered and regrouped based on the kind of predicate (local or join) and the table reference.
重新排序和重新组合谓词是基于谓词的种类(本地或联接)和表引用。
However, if 0 is used in the predicate, a nested-loop join would be the optimal choice instead of merge join.
然而,如果断言中使用的值为0,那么内嵌循环联接可能是最优选择,而不是合并联接。
Thus, the way you write the XMLEXISTS predicate can affect the join order in these previous versions of DB2.
因此,编写xmlexists谓词的方式可以影响以前的DB 2版本连接顺序。
The correct execution plan for this join depends on the optimizer's estimate of how many of PART's 800,000 rows will be selected by the predicate involving P_RETAILPRICE.
这个连接的执行计划的正确性取决于优化器对涉及到P_ RETAILPRICE的谓词将从PART的800,000行中选择多少行这一问题的估计。
When the in predicate is used in its join form, the optimizer still considers it for statistical correlation detection.
当以连接的形式使用in谓词时,优化器将仍会考虑为它检测统计关联。
A guideline to disable the transformation of the in predicate to a join.
一个原则是禁用in谓词到连接谓词的转换。
An outer join can be further restricted by using a predicate.
使用谓词可以进一步限定外部联接。
An outer join can be further restricted by using a predicate.
使用谓词可以进一步限定外部联接。
应用推荐