mqt
美英
- n.牛奶品质测定；牛奶质量测定
- 网络物化查询表(materialized query table)；创建物化查询表；物化查询表(Materialized Query Tables)
mqtmqt
物化查询表(materialized query table)
物化查询表 (MQT) 也是提高查询性能的一种手段，它可以将经常用到的查询结果集存储到一张中间表中，在查询时减少了数据 …
创建物化查询表
2、创建物化查询表（MQT）注意：物化表实际上类似一个查询，没有真正形成表，类型显示为Query。
物化查询表(Materialized Query Tables)
----start DB2 物化查询表MQT（MATERIALIZED QUERY TABLES）存储了一个查询的结果，当我们查询相关表时，DB2会自 …
使用物化查询表
DB2 LUW SQL 调优指南 ... 7. 外连接（ Outer Join） 1. 使用物化查询表（ MQT） 3. 改变优化级别（ Optimization Class） ...
1
You can set up a task in the task center such that the refresh operation of the MQT will happen at a time of your choice.
您可以在任务中心设置任务，使MQT中诸如刷新之类的操作在您选择的时间发生。
2
You can incrementally refresh a REFRESH DEFERRED MQT if it has a staging table associated with it.
如果REFRESHDEFERREDMQT有一个相关联的staging表，那么可以对其执行增量刷新。
3
A materialized query table (MQT) is a table whose definition is based upon the result of a query.
物化查询表（MQT）是一种以一次查询的结果为基础定义的表。
4
The staging table collects changes that need to be applied to synchronize the MQT with its underlying tables.
staging表收集更改，以便应用这些更改，使得MQT与它的底层表同步。
5
The existence of many candidate MQTs might prevent the compiler from choosing the best MQT for that query.
许多备选MQT的存在可能会防止编译器为该查询选择最好的MQT。
6
It gives hints and tips to determine whether an MQT is being used by the query and, if not, what prevented the use of that MQT.
给出用于确定查询是否使用了MQT的提示和技巧，如果未使用，是什么防止了MQT的使用。
7
Other criteria regarding freshness of data in MQT and optimization level used for running the queries are satisfied.
其他条件与MQT中数据的新鲜性和用于运行查询满足的优化级别有关。
8
The article starts out with a motivating example to show how MQTs can help query performance in the Understanding MQTs section.
本文首先在理解MQT一节给出一个启发性例子，展示MQT如何可以改善查询性能。
9
The REFRESH TABLE statement (used for system-maintained MQTs) cannot be issued against user-maintained MQTs.
不能对用户维护的MQT发出REFRESHTABLE语句（用于系统维护的MQT）。
10
Please note that while our workload was defined to use only one MQT per query, it is possible to use multiple MQTs to answer a query.
请注意，尽管我们的工作负载被定义为每个查询只使用一个MQT，但是也可能使用多个MQT来回答一个查询。
11
Once the MQT is created, it needs to be populated with data to reflect the results of the query that the MQT is supposed to cache.
一旦创建了MQT，就需要用数据填充它，以反映MQT将缓存的查询结果。
12
An MQT can be defined at table creation time as maintained by the system or maintained by the user.
MQT可以在创建表时定义，或者定义为系统维护的MQT，或者定义为用户维护的MQT。
13
A replication schedule is automatically set up between the MQT and the nickname on which this MQT is based.
一个复制计划被自动设置在MQT和该MQT所基于的昵称之间。
14
We consider materialized query table (MQT) support an important option to further fine tune the performance of your federated server.
我们考虑物化查询表（MQT）支持一个重要的选项来进一步优化联邦服务器的性能。
15
Our experimentation suggests that when relatively large amounts of data need to be loaded into the MQT, LOAD performs faster than INSERT.
我们的试验表明，当需要将相对较大的数据加载到MQT中时，LOAD执行得比INSERT更快。
16
Make sure that the predicates applied by the MQT are a subset of the predicates applied by the query.
确保MQT应用的谓词是查询应用的谓词的一个子集。
17
Another example is the restriction for XML nicknames that a MQT cannot be created for a child XML nickname.
另一个例子是XML昵称的限制，即不能为子XML昵称创建MQT。
18
The query optimizer will give priority to an execution plan involving an MQT over a plan that involves access to remote tables.
对于涉及到MQT的执行计划，并且该MQT是涉及远程表访问的计划上的MQT，查询优化器给予它优先权。
19
To test the performance of the MQTs over nicknames we used parts of the " TPC-H" benchmark workload adapted to fit a federated environment.
要在昵称上测试MQT的性能，我使用适应于联邦环境的部分“TPC-H”基准测试工作负载。
20
As the data for the base table(s) changes, the MQT needs to be updated accordingly.
当基本表中的数据发生改变时，需要相应地更新MQT。
21
The section walks you through all the steps of creating an MQT, populating it with data, and enabling it for optimization.
这一节详细介绍了创建一个MQT、用数据填充它以及为了优化而启用它的所有步骤。
22
The section on troubleshooting helps you determine why an MQT was not used to satisfy a query.
关于故障诊断的一节帮助您确定为什么没有使用MQT来满足查询。
23
A customer experiences performance issue while refreshing an MQT as part of a batch run.
在批处理运行过程中，当刷新一个MQT时，客户会遇到性能问题。
24
The MQT is populated with the data once and is reused by multiple queries, providing performance benefit.
MQT使用数据填充一次，被多个查询重用，从而带来性能优势。
25
Creation of indexes, unique or otherwise, helps read the data from MQTs in an efficient manner, resulting in better performance.
索引的创建，惟一或不惟一，都有助于以不同的方式从MQT读取数据，导致更好的性能。
26
However, the design of an MQT can be affected by which partitioning features are used on the base table.
然而，MQT的设计却可能受到基本表上使用的分区特性的影响。
27
DW designers may be interested in identifying cases where performance would benefit from converting these logical views to MQTs.
DW的设计者可能对发现能通过将这些逻辑视图转换成MQT来获得性能好处的情况感兴趣。
28
SYSTEM: only the system-maintained MQTs are considered for optimization.
SYSTEM：只为优化考虑系统维护的MQT。
29
The command below removes the user-maintained MQT from the check pending state and enables it for optimization.
下面的命令使用户维护的MQT脱离检查暂挂状态，并启用它，以便进行优化。
30
The MQT must reference the whole hierarchy of nicknames from the root nickname to that child nickname.
MQT必须从根昵称到这个子昵称引用昵称的整个层次结构。