to get (image) statistics

The result times out because there is a large amount of /common/image topics.  Usually, the way to request counts is:

{
  "id" : null,
  "return" : "count",
  "type" : "/common/image"
}

But this will still time out on requests with a large amount of topics.  You could query for the instance count which is tallied nightly:

{
  "/freebase/type_profile/instance_count" : null,
  "id" : "/common/image"
}

but that isn't real-time.

Lastly, you could count yourself by using a cursor and counting until the end of the result set:

{
 "cursor": true,
    "query":  [{
       "id" : null,
     "type" : "/common/image"
    }]
}

To find topics that have an image, you can query for them like so:

[
  {
    "id" : null,
    "image" : [
      {
        "id" : null
      }
    ],
    "type" : "/common/topic"
  }
]

Again, the resultset is very large and will time out, so you will need to cursor and count yourself.

Thanks, that's really helpful!

Now if i'm not mistaken there're about 700K images and 330K topics with image. Does that imply that on average those topics with images each has 2 images? Thanks.

You can just break the link between an image and a topic and not have the image deleted.  Just for fun, I ran a quick analysis:

Found 716008 /common/topic topics with image links (out of ~4 million topics)
650326 have one img
63058 have two imgs
2296 have three imgs
328 have four or more imgs

Thank you. It seems I don't know enough of MQL language; let me know if there's reference other than this website for I don't want to bother you like this.

I use the following code embedded in a perl code to count the number of topics with at least one image, and the result is about 438K--much lower than yours. By the way how to get the number of topics with exactly 1, 2, or 3 images? Can this be requested directly in the query?

{
  "qname":{
    "cursor":

    "query":[{
      "id":null,
      "limit":1000,
      "type":"/common/topic",
      "image":[{
        "id":null
      }]
    }]
  }
}

The following is the code I used. Have a look only if you're free. I print out $count to see number of topics with images and $count~438

Afterwards I grep entire query result and got numbers close to you: 

692001 topics with image

626805 topics with 1 image

62827 topics with 2 images

2210 topcis with 3 images

and so on...

#!/usr/bin/perl
use URI::Escape; 
# This module provides the uri_escape function used below

# Build the Metaweb query, using string manipulation
# CAUTION: the use of string manipulation here makes this script vulnerable
# to MQL injection attacks when the command-line argument includes JSON.
#$band = $ARGV[0]; # This is the band or musician whose albums are to be listed

my $cursor = 'true';
my $query;
my $pre =
'{
    "qname":{
        "cursor":';

my $post = ',
        "query":[{
            "id":null,
            "limit":1000,
            "type":"/common/topic",
            "image":[{
                "return":"count",
                "id":null
            }]
        }]
    }
}';

my $allresult = '';
my $count = 0;
my $result = '';

until($cursor =~ /error/){
#while($cursor){
    $query = $pre . $cursor . $post;

    $escaped = uri_escape($query);

    $baseurl='http://www.freebase.com/api/service/mqlread'; # Base URL for queries
    $url = $baseurl . "?queries=" . $escaped;

    $auth = 'metaweb-user=###Enter Your cookie data here###';

    #$result = `curl -s --cookie \'$auth\' $url`;
    $result = `curl -s $url`;

   
    $result =~ /\/api\/status\/(.*)/;
    $status = $1;

    $result =~ /cursor\":\s*(\".*\")/;
    $cursor = $1;

    $count = $count + 1;

    print $result . "\n";
}

# Use regular expressions to extract the album list from the HTTP response
#$result =~ s/^.*"album"\s*:\s*\[\s*([^\]]*)\].*$/$1/s;
#$result =~ s/[ \t]*"[ \t,]*//g;
#print $allresult ."\n";

print 'done'."\n";
# Finally, display the list of albums
#print "$result\n";
#
# vim: ts=2 sw=2