Question

I’m getting terribly slow results from the following code. I’ve been trying to troubleshoot it for hours but with no results. I’ve included only the relevant code.

Edit:

I am trying to select an id from a database and then use that id to get all the images associated with it. I am then narrowing that group of images down to one. Once I have that image I am resizing it through an external file.

I’ve tried removing various parts of the code to identify the problem and it seems as if the slow down is being caused by the second query but I am not sure why. Thanks for your help.

$getworks = mysql_query ("SELECT a_id from artists where display_works = '1' and active = '1' order by project_year desc, fullname desc");

while ($getworksrow = mysql_fetch_assoc($getworks)){
            $totalimages=1;
            $addstyle = "";
            $id = $getworksrow["a_id"];
            $getimages = mysql_query ("SELECT a_id, image_id from images where a_id = '". $id ."' order by position asc LIMIT 1");
            $getimagesrow = mysql_fetch_assoc($getimages);

            foreach ($getimagesrow as $getimagesrows){
                extract($getimagesrow);

                if($totalimages > 1){ $addstyle = 'style="display:none;"'; }
                else {
                $myimagename = "http://artist.com/$a_id/images/$image_id" .  "_large.jpg";
                list($width, $height, $type, $attr) = getimagesize("$myimagename");
                $myimagename = "http://artist.com/artists/resize.php/$a_id/images/$image_id" . "_large.jpg?resize(157x2000)";

                if($getworksrows["layout"] == "vert"){$pl = "_vertical";}else if($getworksrows["layout"] == "website"){$pl = "-s";}else if($getworksrows["layout"] == "video"){$pl = "_video";}else{$pl = "_horizontal";}
                echo "<li class='thumbnail_container' $addstyle> <a class='thumbnail' href=\"../works$pl.php?a_id=" . $getworksrows["a_id"] . "\"><span><img src=\"$myimagename\" /></span>\n</a></li>\n";
                }

                $totalimages++;
            }

}

Answer 1

It’s a a big performance overhead to execute queries like this specially when parent query have large no. of records.

You should use join artists table with images table and get all data by single query.

Later on make 2D array of per artists and images. and loop according to 2D array to display data

Below is join query you should use:

SELECT * from artists as art 
left join images as img  on art.a_id=img.a_id 
where display_works = '1' and active = '1' 
order by project_year desc, fullname desc

In While make data array:

   while ($getworksrow = mysql_fetch_object($getworks)){

    $data['a_id']['img_id']=$getworksrow->image;  //Make 2D array
   ........
   ........

    }

looping and display data :

foreach($data as $id=>$images)
{
   foreach($images as $val){
     // Do your stuff for displaying data
   }

}

So please do required changes.