Query String Size

cfouquet · July 21st, 2004, 05:50 AM

What is the max size of a query string allowed?

Is there a limit imposed by the Http protocol?

stu9820 · July 21st, 2004, 07:49 AM

There is a limit using querystring values but I can't remember the exact size. That's why ASP.NET uses the POST method that allows more data to be passed back to itself (since ASP.NET POSTs to the same page).

Colonel Angus · July 27th, 2004, 08:40 AM

I believe it's 255 characters.

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In God we trust, everything else we test.

funtent · July 27th, 2004, 11:01 AM

It's more than 255 characters. At my previous job we were concerned about hitting the limit (we overused the qs, you could say) and losing data. We tested it to, and above, 2k of text.

But -- I think older browsers may truncate at 2k. Be careful with those.

For an example of huge qs's, look at any RealNetworks product's order path.

melvik · August 1st, 2004, 12:23 AM

as Colonel since ASP 3.0 I do believe it's 255 characters or .Net removed the limiration I diudnt test this time.

Always:),
Hovik Melkomian.

Imar · August 1st, 2004, 04:36 AM

No way. It's much longer than 255 characters, and that was also the case in classic ASP. I don't even think it's a server side problem, but a browser restriction. Here's a simple test.
Create two pages, QueryString1.asp and QueryString2.asp. In the first, add the following code that creates a string of 2000 characters, appends it to an URL as a QueryString and then redirects to that:

Code:

<%
  Dim queryString
  Dim loopCount

  For loopCount = 1 To 2000
    queryString = queryString & Right(CStr(loopCount), 1)
  Next
  Response.Redirect("QueryString2.asp?QUERY=" & queryString)
%>

On QueryString2.asp add code that writes out the QueryString and its length:

Code:

<%
  Response.Write("The QueryString is " & _
      Request.QueryString & "<br />")
  Response.Write("It has a length of " & _
      Len(Request.QueryString) & "<br />")
%>

When you open QueryString1.asp in your browser, you'll see it successfully redirects to QueryString2.asp where it displays the QueryString and a length of 2006 (QUERY= is counted as well).

In Internet Explorer, I can loop up to 2034 so the entire QueryString is 2040 characters. After that, the code stops working.
However, other browsers have different limitations. In FireFox 0.X I can successfully pass QueryStrings of 6000 characters and more (haven't tested the upper limit yet).

The same is True for Opera 7 (5 and 6 show the correct length, but no longer display the QueryString), Netscape (4, 6 and 7) and Mozilla.

So since Internet Explorer 6 is one of the most used browsers, it's recommended to keep the length of the QueryString under 2000 characters.

Hope this clarifies the QueryString myth a little bit.

Cheers,

Imar
---------------------------------------
Imar Spaanjaars
Everyone is unique, except for me.
While typing this post, I was listening to: Creamer (Radio Is Dead) by Limp Bizkit (Track 13 from the album: Results May Vary) What's This?