Jet Engine的查询优化基于统计信息，但是如何使用链接表刷新它们呢? [英] Jet Engine's query-optimization is based on statistics, but how are they refreshed with linked tables?

问题描述

我正在处理某些旧式访问权限< 2007年数据库".所有表都是链接到SQL Server 2008的表.建立odbc链接时，表结构与DSN字符串一起复制到mdb文件中.那就是在Msysobjects中可以看到的东西.

i am dealing with some legacy access < 2007 "databases". All the tables are linked tables to a SQL Server 2008. While the odbc-links are established the table structure is copied into the mdb-file together with the DSN-string. Thats what one can see in Msysobjects.

查询会根据喷气发动机的优化情况，强制喷气发动机从SQL Server检索数据.因此，每当更改sql server时都必须刷​​新odbc链接，就像添加新的索引参数示例一样.

A query forces the jet-engine to retrieve the data from SQL Server under respect of the jet-engines optimization. Therefore it is essential to refresh the odbc-links whenever a change in sql server is made, like adding a new index par example too.

随着某些表的增大，射流优化器需要刷新统计信息，但这是哪个过程?是维修与保养吗?压缩还是刷新ODBC链接?可以通过编程方式完成吗?

As some tables grow larger the jet-optimizer needs refreshed statistics but which process does that? Is it Repair & Compact or refreshing the ODBC-Links? Can this be done programatically?

和平

冰

推荐答案

JET做出良好的优化决策所需的最重要的事情是表上的正确索引.您可以通过在设计模式下打开链接表(ODBC)并单击索引图标来检查JET可以看到哪些索引.您会得到警告，说这些表是只读的.

The most important thing that JET needs to make good optimisation decisions is correct indices on tables. You can check what indices are visible to JET by opening a linked tables (ODBC) in design mode and clicking on the indices icon. You will get a warning to say that the tables are read-only.

在执行查询时，在源表上创建索引可能比等待JET建立优化元数据更有效.

Creating indices on source tables is likely to be more effective that waiting for JET to build up optimisation meta data when queries are executed.

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