Question

I have two MySQL tables:

• attributes (attributeid, name)
• productsattributes (productid, attributeid, displayvalue)

The required is for each attribute name called “Product Type” get all other attributes associated with this “Product Type”. As an example — attributes table will look like:

    attributeid  name
    1            A
    2            B
    3            Product Type
    4            D

productsattributes table will look like:

productid attributeid displayvalue
        1         3           FAN
        1         1           Brown
        1         2           Stand
        2         3           FAN
        2         4           D
        3         3           CAR
        3         4           imported

So the final result should be:

FAN (A,B, Product Type,D) 
CAR (Product Type, imported)

Here is my try:

• first I get all the “displayvalues” from productattributes:

SELECT DISTINCT displayvalue 
  FROM productsttributes 
 WHERE attributeid = 3;

• then I loop through each “displayvalues” to find the other attributes:

SELECT a.name 
 FROM attributes a 
 INNER JOIN productsattributes pa 
    ON pa.attributeid = a.attributeid AND productid in (
        SELECT productid 
        FROM productsttributes 
        WHERE dispalyvale =  '$displayvalue') 
 ORDER BY a.name;

The problem is the productattributes table has about 7 million rows, so my script is taking forever .. of course I am not looking for 10 minutes solution but at least it will improve my queries a bit.

Answer 1

I would start with the following statements:

ALTER TABLE attributes ADD CONSTRAINT p_attributes PRIMARY KEY (attributeid);
ALTER TABLE productsattributes ADD CONSTRAINT p_productsattributes
    PRIMARY KEY(productid, attributeid);
ANALYZE TABLE attributes, productsattributes;

This will make sure all important fields are indexed.

The query might look like this (also on SQL Fiddle):

SELECT trg.displayvalue,
       group_concat(a.name ORDER BY trg.productid, a.attributeid)
  FROM (
        SELECT t.productid,t.displayvalue
          FROM attributes a
          JOIN productsattributes t USING (attributeid)
         WHERE a.name = 'Product Type') AS trg
  JOIN productsattributes p ON p.productid = trg.productid
  JOIN attributes a ON a.attributeid = p.attributeid
 GROUP BY trg.displayvalue
 ORDER BY 1;

Please, kindly include the EXPLAIN output of your’s and this queries into your question.