Each step in a path expression can also contain a predicate that filters the elements that are returned by that step, retaining only elements that satisfy some condition.
路径表达式中的每一步还可以包含一个谓词，用于过滤该步返回的元素，只保留满足某种条件的元素。
Before access path selection, the DB2 optimizer transforms SQL statements into forms that are semantically identical, such as by using predicate pushdown or predicate transitive closure.
在选择访问路径之前，DB 2优化器将sql语句转换成语意上一致的形式，例如使用谓词下推或谓词传递闭包。
Missing statistics can cause the optimizer to overestimate or to underestimate the selectivity of a predicate, and eventually to select an inefficient access path.
丢失的统计数据会让优化器高估或低估谓词的选择性，最终会选择低效的访问路径。
The index does not contain "price" elements at a deeper level, which may exist in the table and are potential matches for the predicate path $i//price.
索引没有包含更深层次的 “price”元素，表中可能存在该元素且可能与谓词路径 $i//price 相匹配。
Just as each progressive portion of an XPath is based on the set of nodes determined by the preceding path, the predicate of a set is based on the set that you apply it to.
就像XPath后面的部分依赖于前面路径所决定的节点集一样，集合的谓词也依赖于所应用的集合。
The predicate in the WHERE clause constrains the relational column office, which the view maps to the path /dept/employee/office in the XML column.
WHERE 子句中的谓词限制关系列office，而视图把这一列映射到XML 文档中的路径 /dept/employee/office。
The predicate in the WHERE clause constrains the relational column office, which the view maps to the path /dept/employee/office in the XML column.
WHERE 子句中的谓词限制关系列office，而视图把这一列映射到XML 文档中的路径 /dept/employee/office。
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