Delay effect with Pervasive.SQL client cache engine

Solution Details

Solution ID: 00016865
What is the Client Cache engine ?

Problem Description:

Problem Environment:
Pervasive.SQL V8

Cause of this problem:

Solution Notes:
The client cache engine is essentially a MicroKernel database engine that stores recently-used data file pages in local memory on the client workstation. Future reads will access the client cache first prior to sending a request across the network to re-read the records. This can yield significant increases in performance as it reduces the data flowing across the network (network traffic). However, the data that is stored in the client cache is static data, and is refreshed after a maximum of every 5 seconds delay by default.

In some environments, the application behavior cannot tolerate this delay, and the client cache engine should be disabled. Also, in other environments where there are a very large number of clients connected to the server the polling between the client and the server can increase the network traffic and actually reduce performance.

Other factors such as application architecture can make a tremendous difference in the ability of the client cache engine to be used efficiently.
For transactional API applications the client cache engine is bypassed in the following circumstances:

• q Opens / Closes / Resets - are processed both locally and passed through to the server engine
• q Insert / Update / Delete (any write operation) is passed through to the server engine q Anything inside a transaction is passed through to the server engine
• q Any operation with a lock bias is passed through to the server engine The relational API is client / server in nature and all processing is performed at the server. As such the client cache engine is not used for SQL / ODBC access.

For more information on the Client Cache Engine, consult the " What's New..." and the "Advanced Operations Guide" on-line manuals which are available with the Pervasive.SQL V8 documentation.

http://www.pervasive.com/kb/kb.asp?fx=getdetails&solid=00016865&title=What%20is%20the%20Client%20Cache%20engine

จากคำอธิบายเกี่ยวกับ cache engine ของ Pervasive 8 จะเห็นว่า ข้อดีของ cache engine คือ ลดปริมาณ traffic ใน network ลง ทำให้การทำงานเร็วขึ้น แต่ก็จะมีปัญหา delay ของข้อมูล เมื่อคอมพิวเตอร์เครื่องหนึ่ง update ข้อมูลไปแล้ว กว่าที่คอมพิวเตอร์อีกเครื่องหนึ่งจะทำการ refresh cache engine จะต้องรอทุกๆ 5 วินาที แต่เท่าที่ผ่านมา ปัญหานี้ยังไม่ถูกสังเกตพบจนกลายเป็นปัญหาจากผู้ใช้ครับ