如何获取从file_get_contents（）派生的内容的大小

I m using this technique to store the image as blob in mysql

INSERT INTO aw_offers_v2
                    (
                    id,name,description,payout_type,
                    payout,expiration_date,creation_date,preview_url,
                    tracking_url,categories,countries,countries_short,
                    api_key,network_id, icon)
                    VALUES
                    ('$id','$name','$description','$payout_type',
                    '$payout','$expiration_time','$creation_time','$preview_url',
                    '$tracking_url','$categories','$countries','$countries_short',
                    '$api','$api_url','".mysql_real_escape_string(file_get_contents($cover_image_src))."')

now the issue is, how can i get the size of the blob element and store it in another field

say if the blob is 5.34kb i need to get it and store into another field called blob_size

Assuming the content is located in the URL $cover_image_src, you can use following technique to get the size,

$headers = get_headers($cover_image_src, 1);
$content_length = $headers["Content-Length"];

Easy way - you can use strlen( file_get_contents($cover_image_src) )