• This query plan shows full table scans.

    查询计划显示了扫描

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  • You may notice excessive Numbers of table scans.

    也许注意到被扫描过多

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  • However, block locking was not be deferred for table scans.

    然而对于扫描不会推迟

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  • This is a lot faster than a nested loop join of two table scans without any index usage.

    使用任何索引两个扫描嵌套循环连接要快得

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  • This will allow both of the following queries to use indexed access rather than table scans.

    允许下面两个查询使用索引访问不是扫描。

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  • Contiguity of physical data or keys is important to the speed of table scans or key-index scans.

    物理数据连续性对于扫描-索引扫描的速度十分重要

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  • This makes DB2 queries use table scans instead of index scans and degrades database performance.

    使得DB 2查询使用表扫描代替索引扫描,降低了数据库性能

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  • The number of table scans reported represents the scans on the table between 1:00 p.m. and 2:00 p.m.

    报告扫描次数表示下午 1到 2 点之间这个表上执行的扫描。

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  • Perform index analysis to make sure that the right indexes exist to help avoid unnecessary table scans.

    执行索引分析确保索引正确,从而避免不必要的扫描

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  • You can use the Design Advisor to see if indexes would result in an access plan with fewer table scans.

    那么这时可以使用Design Advisor,看看索引是否能导致不需要扫描那么多访问计划

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  • Also as shown in Figure 11, you can see that there are still two table scans for each execution of the query.

    还是如图11所示,每次执行查询都两个扫描

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  • The costs of table scans can be fairly low if the data in the table is clustered or if it is in physical order.

    如果中的数据进行群集化处理,或者物理次序的,那么表扫描成本可能相当

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  • Fragmentation and PDQ priority also have a huge effect on the speed of data retrieval and will help table scans.

    分段PD Q优先级对于数据检索速度极大影响有助于扫描

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  • A high value here can indicate excessive table scans that can be prevented by creating indexes on the predicate columns.

    如果该很大表示可以通过谓词创建索引避免多余扫描

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  • Creating indexes helps avoid unnecessary table scans and sorts, speeds up frequently executed queries, and ensures uniqueness.

    索引创建有助于避免进行不必要扫描排序加速频繁执行查询以及确保惟一性

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  • It's also optimized for full table scans (one of the most common-and most time-consuming-business intelligence query access patterns).

    针对完全扫描(一个常见—也最耗时—的商业智能查询访问模式)进行了优化

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  • Because of the number of table scans and table sorts in the TPC-H workload, prefetching data from disks into memory is important for optimal performance.

    因为TPC - H工作负载中表扫描排序数量较多,所以获得最佳性能数据磁盘内存很重要的。

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  • If the value is set to 0, then the optimizer chooses index scans over table scans if appropriate indexes exist, without even considering the estimated costs.

    如果设置0,那么存在合适索引时,优化器就选择索引扫描扫描,甚至不考虑估算成本。

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  • Tuning can include adding extra indexes to yield a more efficient access plan, which makes tables volatile to encourage index usage and avoid table scans if possible.

    调优包括添加额外索引生成一个高效访问计划表格变幻无常进而鼓励索引使用如果可能的话也可以避免扫描

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  • DB2 row compression features can decrease disk storage requirements while at the same time improve sequential read access of large queries which perform full table scans.

    DB 2压缩功能可以减少磁盘存储需求同时改进执行扫描大量查询顺序读取访问

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  • Prefetching is used when the Database Manager determines that sequential I/O is appropriate and that prefetching can help to improve performance (typically large table scans).

    数据库管理器确定顺序I/O适当的并且确定取操作可能有助于提高性能时,会使用预取操作(通常大型扫描)。

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  • 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.

    如果连接一个索引那么其成本会相当否则数据库服务器就必须所有(外部内部表)执行扫描

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  • When it finds an active partition, it scans the remaining partitions in the table to ensure that they're all inactive.

    找到一个活动分区时,会扫描分区中的其他分区确保它们不是活动的。

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  • Index scans are usually the most efficient way to access data, especially when the table is large but the number of qualified rows is small.

    一般来说索引扫描访问数据有效方法尤其是很大符合条件很少时候

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  • This locking was done for both index scans and table access whether or not the row of data was committed or whether it would have been excluded based on the statement's predicates.

    不管数据是否提交以及根据语句谓词是否排除对于索引扫描访问执行这样锁定操作。

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  • For multiple index push-downs, multi-index scan is used to combine RIDs from different index scans, then skip-scan on the fact table is performed.

    对于索引下推,多索引扫描用于组合来自不同索引扫描RID然后就可以执行事实的跳跃式扫描了。

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  • The first-stage boot loader scans the table, looking for the active partition; when the loader locates the partition, it loads the second-stage boot loader into RAM and invokes it.

    第一阶段的引导加载程序进行扫描查找活动分区加载程序找到分区时,第二阶段的引导加载程序加载RAM中调用

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  • When DB2 scans a table, only the segments associated with that table are accessed.

    DB2扫描一个时,只是访问那个相关

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  • The MON_GET_INDEX table function and db2pd utility provide the same index metrics (number of index scans and index only scans).

    MON_GET_INDEX函数db2pd实用程序提供相同索引度量指标扫描索引和扫描索引的数量)。

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  • Furthermore, deleted rows are skipped unconditionally on table scan access while deleted keys are not skipped for type-2 index scans unless the registry variable DB2_SKIPDELETED is also set.

    而且虽然在type - 2索引扫描中,删除不会跳过,但是除非同时设置注册表变量db2_skipdeleted,否则扫描访问中,被删除的行将被无条件跳过。

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