Microsoft Jet 3,5 Performance Overview and Optimization Techniques. Non-configurable Performance Settings, страница 13

--------------------------------------------DATE: 01/19/97

VER:  3.50.3428

NOTE: Currently does not handle subqueries, vt [virtual table] parameters, and subqueries

NOTE: You may see ERROR messages in these cases

--- Invoices --- Inputs to Query Table 'Orders'

Table 'Order Details'

Using index 'OrdersOrder Details'

Having Indexes:

OrdersOrder Details 2155 entries, 8 pages, 830 values

which has 1 column, fixed

OrderID 2155 entries, 8 pages, 830 values

which has 1 column, fixed

Table 'Customers'

Using index 'PrimaryKey'

Having Indexes:

PrimaryKey 91 entries, 1 page, 91 values

which has 1 column, fixed, unique, primary-key, no-nulls

PostalCode 91 entries, 1 page, 87 values

which has 1 column, fixed

CompanyName 91 entries, 3 pages, 91 values

which has 1 column, fixed

City 91 entries, 1 page, 69 values

which has 1 column, fixed

Table 'Employees'

Table 'Products'

Table 'Shippers'

- End inputs to Query 01) Sort table 'Orders'

02) Inner Join table 'Shippers' to result of '01)'

using temporary index

join expression "Shippers.ShipperID=Orders.ShipVia"

03) Sort table 'Employees'

04) Inner Join result of '02)' to result of '03)'

using temporary index

join expression "Orders.EmployeeID=Employees.EmployeeID"

05) Inner Join result of '04)' to table 'Customers'

using index 'Customers!PrimaryKey'

join expression "Orders.CustomerID=Customers.CustomerID"

06) Inner Join result of '05)' to table 'Order Details'

using index 'Order Details!OrdersOrder Details'

join expression "Orders.OrderID=[Order Details].OrderID"

07) Sort table 'Products'

08) Inner Join result of '06)' to result of '07)'

using temporary index

join expression "[Order Details].ProductID=Products.ProductID"

--- temp query --- Inputs to Query Table 'Customers'

Using index 'CompanyName'

Having Indexes:

CompanyName 91 entries, 3 pages, 91 values

which has 1 column, fixed

City 91 entries, 1 page, 69 values

which has 1 column, fixed

- End inputs to Query 01) Scan table 'Customers'

Using index 'CompanyName'

--- temp query --- Inputs to Query Table 'Products'

Using index 'ProductName'

Having Indexes:

ProductName 77 entries, 1 page, 77 values

which has 1 column, fixed

PrimaryKey 77 entries, 1 page, 77 values

which has 1 column, fixed, unique, clustered and/or counter, primary-key, no-nulls

CategoryID 77 entries, 1 page, 8 values

which has 1 column, fixed

CategoriesProducts 77 entries, 1 page, 8 values

which has 1 column, fixed

- End inputs to Query 01) Scan table 'Products'

Using index 'ProductName'

Conclusion

The Jet team takes performance very seriously and has had a dedicated team for performance since Jet 3.0. However, even with our 1,500 plus performance tests, we cannot encounter all the scenarios that our customers put Jet through. If you believe that you have encountered a performance issue with Jet, please contact Microsoft support with a precise reproducible scenario. They will forward this information to the Jet performance team and we will examine it and try to come up with workarounds or attempt to correct the issue in the next release of Jet.

Another method of letting the Jet team know about features or performance requests specific to the Jet database engine is to e-mail us at JetWish@Microsoft.com.

If this paper interests you, I would highly recommend purchasing the Microsoft Jet Database Engine Programmer’s Guide by Microsoft Press. While it does not address Jet 3.5 (a revised release is currently being planned) it does have pertinent information on understanding how Jet works and the best ways to utilize Jet.