MySQL Views – How to Mimic a Full Outer Join Using MySQL Views

You don't need all the derived tables. You are joining the basic (product) too many times. You can write the query joining it only once.

Compound indices are a must for EAV designs. Try adding an index on (attribute_id, product_id, value) and then the query:

SELECT t0.id, 
       t1.`value` AS length, 
       t2.`value` AS height, 
       t3.`value` AS family
FROM
  products t0

INNER JOIN 
  product_eav_decimal t1
    ON  t1.product_id = t0.id  
    AND t1.attribute_id = 91
    AND t1.`value` BETWEEN 15 AND 35

LEFT JOIN
  product_eav_decimal t2
    ON  t2.product_id = t0.id  
    AND t2.attribute_id = 80  
-- 
-- 
--

LEFT JOIN                              -- LEFT or INNER join
  product_eav_decimal t6
    ON  t6.product_id = t0.id  
 -- AND t6.attribute_id = 

ORDER BY t0.id ASC ;

Try this

select a.Date, a.Foo, b.Bar
from TableA a LEFT JOIN TableB b ON a.Date = b.Date
UNION
select b.Date, a.Foo, b.Bar
from TableB b LEFT JOIN TableA a ON a.Date = b.Date

Strictly speaking, the query above does not quite have the same semantics as the original full join, with respect to duplicates. A correct transformation of full join is to a left join union all anti-semi-join:

SELECT 
    TA.TheDate, 
    TA.Foo, 
    TB.Bar
FROM dbo.TableA AS TA
LEFT JOIN dbo.TableB AS TB 
    ON TB.TheDate = TA.TheDate
UNION ALL
SELECT 
    TB.TheDate, 
    Foo = NULL, 
    TB.Bar 
FROM dbo.TableB AS TB
WHERE NOT EXISTS 
(
    SELECT NULL
    FROM dbo.TableA AS TA 
    WHERE TA.TheDate = TB.TheDate
);

This second rewrite will also facilitate the use of an index on TheDate columns.