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Question

I currently have a client-server application. The client needs to be able to generate reports. These reports can have millions of records. What is the best way to get the data to the client? Sending all million records at once is not very efficient. Let's say I just want to display 20 at a time and page through all the results. Would I have the server do the query each time a user clicks on next page or should I have the server get the entire result set and then sent parts of it to the client?

Answer 1

Use a cursor - it is perfect for these purposes.

Note - a report with million rows is not well designed report. Nobady can process it. But this is question for analytic.

http://www.commandprompt.com/ppbook/x15040

Answer 2

I used Limit in sql query to set a range of records fetched. but the query has to originate from client and the query must pass the range.

It depends on scripting, if you use Dotnet+npgsql connector

• I would generate a Pagenumber in a combobox on form
• Then multiply the pagenumber with Rows*(pagenum-1) (20*1 for page2) to get starting rownum
• Pass it in form of sql to database
• Retrieve rows and display in datagridview

Although, i might just add, searching through a million record Page_by_page is not wisdom. i hope there are some filters to narrow down search to a few pages. Because research show that views beyond page10 drop exponentially.