Need help to tune a complex query - mysql

Question

I am trying to performance tune a query and need help with that
We have a requirement to pull in data on the website based on multiple factors which resulted in a complex query which works fine but is expensive. We have all the correct indexes.
What I am stuck on is removing the use of DISTINCT in the query (which seems to be the bottleneck).
I am no SQL expert and I think I've tried everything I could.
Any help to simplify this query and remove DISTINCT (or not use GROUP BY) will be much appreciated. Thanks.
SELECT DISTINCT t2.PK
FROM categories t0
JOIN cat2catrel t1 ON t1.SourcePK = t0.PK
JOIN categories t2 ON t1.TargetPK = t2.PK
JOIN cat2catrel t3 ON t3.SourcePK = t2.PK
JOIN categories t4 ON t3.TargetPK = t4.PK
JOIN cat2prodrel t5 ON t5.SourcePK = t4.PK
JOIN products t6 ON t5.TargetPK = t6.PK
JOIN stocklevels t7 ON t7.productcode = t6.code
JOIN relativeinventory t8 ON t7.p_inventory = t8.PK
JOIN warehouses t9 ON t7.warehouse = t9.PK
JOIN pos2warehouserel t10 ON t10.TargetPK = t9.PK
JOIN pos2warehouserel t10 ON t10.TargetPK = t9.PK
JOIN pointofservice item_t11 ON t10.SourcePK = t11.PK
WHERE ( t0.code = 'code'
AND t8.nventorystatus IN (1111)
AND t11.name = 'ABC')
AND ((t0.TypePkString IN (1, 2, 3, 4)
AND (( t0.catalogversion IN (1, 2, 3)))
AND t1.TypePkString=1000
AND t2.TypePkString IN (1, 2, 3, 4)
AND (( t2.catalogversion IN (1, 2)))
AND t3.TypePkString=300
AND t4.TypePkString IN (6, 7, 8)
AND (( t4.catalogversion IN (5, 6)))
AND t5.TypePkString=500
AND t6.TypePkString=600
AND t7.TypePkString=200
AND t8.TypePkString=700
AND t9.TypePkString IN (3, 7)
AND t10.TypePkString=900
AND t11.TypePkString=750 ));
Currently, this query works fine and provides the results I want. I just don't want to use DISTINCT or GROUP BY and still get unique results.
DB: MySQL 6.3

Answer 1

Your only selecting t2.pk, which appears to be the primary key in the categories table. If this is correct, your producing duplication with your Joins. The easiest solution in general to get rid of DISTINCT in this scenario is to start with the table that you are selecting from and ensuring your INNER JOINING to it. However, it appears your actually doing this already, but your duplicating the join... i.e. t0 and t2 are the same table which is a big red flag to me. Try something like this:
SELECT t0.PK
FROM categories t0
INNER JOIN cat2catrel t1 ON t1.SourcePK = t0.PK AND t1.TargetPK = t0.PK
INNER JOIN cat2catrel t3 ON t3.SourcePK = t0.PK
INNER JOIN categories t4 ON t3.TargetPK = t4.PK
INNER JOIN cat2prodrel t5 ON t5.SourcePK = t4.PK
INNER JOIN products t6 ON t5.TargetPK = t6.PK
INNER JOIN stocklevels t7 ON t7.productcode = t6.code
INNER JOIN relativeinventory t8 ON t7.p_inventory = t8.PK
INNER JOIN warehouses t9 ON t7.warehouse = t9.PK
INNER JOIN pos2warehouserel t10 ON t10.TargetPK = t9.PK
INNER JOIN pos2warehouserel t10 ON t10.TargetPK = t9.PK
INNER JOIN pointofservice item_t11 ON t10.SourcePK = t11.PK
WHERE ( t0.code = 'code'
AND t8.nventorystatus IN (1111)
AND t11.name = 'ABC')
AND ((t0.TypePkString IN (1, 2, 3, 4)
AND (( t0.catalogversion IN (1, 2, 3)))
AND t1.TypePkString=1000
AND t2.TypePkString IN (1, 2, 3, 4)
AND (( t2.catalogversion IN (1, 2)))
AND t3.TypePkString=300
AND t4.TypePkString IN (6, 7, 8)
AND (( t4.catalogversion IN (5, 6)))
AND t5.TypePkString=500
AND t6.TypePkString=600
AND t7.TypePkString=200
AND t8.TypePkString=700
AND t9.TypePkString IN (3, 7)
AND t10.TypePkString=900
AND t11.TypePkString=750 ));
However I see other tables duplicated to like "pos2warehouserel". Tables should only be declared and assigned an alias once.