Codeigniter database call efficiency - mysql

Question

This is an efficiency/best practice question. Hoping to receive some feed back on performance. Any advice is greatly appreciated.
So here is a little background in what i have setup. I'm using codeigniter, the basic setup is pretty similar to any other product relationships. Basic tables are: Brands, products, categories. On top of these tables there is a need for install sheets, marketing materials, and colors.
I created some relationship tables:
Brands_Products
Products_Colors
Products_Images
Products_Sheets
I also have a Categories_Relationships table that holds all of the relationships to categories. Install sheets etc can have their own categories but i didn't want to define a different category relationship table for each type because i didn't think that would be very expandable.
On the front end I am sorting by brands, and categories.
I think that covers the background now to the efficiency part. I guess my question pertains mostly to weather it would be better to use joins or to make separate calls to return individual parts of each item (colors, images, etc)
What I currently have coded is working, and sorting fine but I think i can improve the performance, as it take some time to return the query. Right now its returning about 45 items. Here is my first function it grabs all the products and its info.
It works by first selecting all the products and joining it's brand information. then looping through the result i set up the basic information, but for the categories images and installs i am using functions that returns each of respected items.
public function all()
{
$q = $this->db
->select('*')
->from('Products')
->join('Brands_Products', 'Brands_Products.product_id = Products.id')
->join('Brands', 'Brands.id = Brands_Products.brand_id')
->get();
foreach($q->result() as $row)
{
// Set Regular Data
$data['Id'] = $row->product_id;
$data['Name'] = $row->product_name;
$data['Description'] = $row->description;
$data['Brand'] = $row->brand_name;
$data['Category'] = $this->categories($row->product_id);
$data['Product_Images'] = $this->product_images($row->product_id);
$data['Product_Installs'] = $this->product_installs($row->product_id);
$data['Slug'] = $row->slug;
// Set new item in return object with created data
$r[] = (object)$data;
}
return $r;
}
Here is an example of one of the functions used to get the individual parts.
private function product_installs($id)
{
// Select Install Images
$install_images = $this->db
->select('*')
->where('product_id', $id)
->from('Products_Installs')
->join('Files', 'Files.id = Products_Installs.file_id')
->get();
// Add categories to category object
foreach($install_images->result() as $pImage)
{
$data[] = array(
'id' => $pImage->file_id,
'src' => $pImage->src,
'title' => $pImage->title,
'alt' => $pImage->alt
);
}
// Make sure data exists
if(!isset($data))
{
$data = array();
}
return $data;
}
So again really just looking on advice on what is the most efficient, best practice way of doing this. I really appreciate any advice, or information.

Answer 1

I think your approach is correct. There are only a couple of options: 1) load your product list first, then loop, and load required data for each product row. 2) create a big join on all tables first, then loop through (possibly massive) cartesian product. The second might get rather ugly to parse. For example, if you got Product A and Product B, and Product A has Install 1, Install 2, Install 3, and product B has Install 1, and Install 2,t hen your result is
Product A Install 1
Product A Install 2
Product A Install 3
Product B Install 1
Product B Install 2
Now, add your images and categories to the join and it might become huge.
I am not sure what the sizes of your tables are but returning 45 rows shouldn't take long. The obvious thing to ensure (and you probably did that already) is that product_id is indexed in all tables as well as your brands_products tables and others. Otherwise, you'll do a table scan.
The next question is how you're displaying your data on the screen. So you're getting all products. Do you need to load categories, images, installs when you're getting a list of products? If you're simply listing products on the screen, you might want to wait to load that data until user picks a products they are viewing.
On a side note, any reason you're converting your array to object
$r[] = (object)$data;
Also, in the second function, you can simply add
$data = array();
before the foreach, instead of
// Make sure data exists
if(!isset($data))
{
$data = array();
}

Answer 2

You can try this:
Query all of the products
Get all of the product IDs from step 1
Query all of the install images that has a product ID from step 2, sorted by product ID
Iterate through the products from step 1, and add the results from step 3
That takes you from 46 queries (for 45 products) to 2 queries, without any additional joins.
You can also use CodeIgniter's Query Caching to increase performance even further, if it's worth the time to write the code to reset the cache when data is updated.
Doing more work in PHP is generally better than doing the work in MySQL in terms of scalability. You can scale PHP easily with load balancers and web servers. Scaling MySQL isn't as easy due to concurrency issues.