如何防止 Crystal webserver 在每个页面上重新获取数据 [英] How to prevent Crystal webserver refetching data on each page

问题描述

We're using Crystal 11 through their webserver. When we run a report, it does the Sql query and displays the first page of the report in the Crystal web reportviewer.

When you hit the next page button, it reruns the Sql query and displays the next page.

How do we get the requerying of the data to stop?

We also have multiple people running the same reports at the same time (it is a web server after all), and we don't want to cache data between different instances of the same report, we only want to cache the data in each single instance of the report.

解决方案

The reason to have pagination is not only a presentation concern. With pagination the single most important advantage is lazy loading of data - so that in theory, depending on given filters, you load only what you need.

Just imagine if you have millions of records in your db and you load all of them. First of all is gonna be a hell of a lot slower, second you're fetching a lot of stuff you don't really need. All the web models nowadays are based on lazy loading rather than bulk loading. Think about Google App Engine: you can't retrieve more than 1000 records in a given transaction from the Google Datastore - and you know that if you'll only try and display them your browser will die.

I'll close with a question - do you have a performance issue of any kind?

If so, you probably think you'll make it better but it's probably not the case, because you'll reduce the load on the server but each single query will be much more resource consuming. If not my advice is to leave it alone! :)

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