Full outer join very slow - sql

Question

I have two tables. One is todays prices and one is yesterdays prices. There is a job which updates each table over night. Yesterdays prices is a copy of todays before it gets updated.
I am trying to create a table which shows the differences between the tables.
To do this I am using a full outer join. I am filtering down my criteria to make it faster as both tables are over 48 million rows.
My current code is like this.
WITH differ AS
(
SELECT
tAP.CustomerID, tAP.ProductID, yAP.CustomerID AS 'Yest_CustomerID', yAP.ProductID AS 'Yest_ProductID',
tAP.PDG, tAP.DiscPct1, tAP.DiscPct2,
yAP.DiscPct1 AS 'Yest_DiscPct1',
yAP.DiscPct2 AS 'Yest_DiscPct2',
CONVERT(DECIMAL(18,2),tAP.DiscPct1 - yAP.DiscPct1) AS 'DiscPct1_Difference',
CONVERT(DECIMAL(18,2),tAP.DiscPct2 - yAP.DiscPct2) AS 'DiscPct2_Difference',
tAP.internalSPANumber, yAP.internalSPANumber AS 'Yest_InternalSPANumber', tAP.SPAUniqueReference,
tAP.Project,
tAP.ExpiryDate,tAP.Subaddress, tAP.PriceType, yAP.PriceType AS 'Yest_PriceType', tAP.ListPrice,
tAP.NettPrice, yAP.NettPrice AS 'Yest_NettPrice',
CONVERT(DECIMAL(18,2),tAP.NettPrice- yAP.NettPrice) AS 'NettPrice_Difference'
FROM tbl_Prices tAP FULL OUTER JOIN tbl_Prices_Yesterday yAP ON tAP.CustomerId = yAP.CustomerID AND tAP.ProductID = yAP.ProductID
AND tAP.PDG = yAP.PDG AND tAP.Project = yAP.Project AND tAP.PriceType = yAP.PriceType
WHERE (((tAP.DiscPct1 <> yAP.DiscPct1)
OR (tAP.DiscPct2 <> yAP.DiscPct2)
OR (yAP.CustomerID IS NULL)
OR (tAP.CustomerID IS NULL)
OR (tAP.NettPrice <> yAP.NettPrice)
OR (tAP.InternalSPANumber <> yAP.InternalSPANumber))
AND
(
tAP.ProductID = '10238610' OR tAP.ProductID = '10238620'
OR tAP.ProductID = '10238621' OR tAP.ProductID = '10238687'
OR tAP.ProductID = '10238688' OR yAP.ProductID = '10238610'
OR yAP.ProductID = '10238620' OR yAP.ProductID = '10238621'
OR yAP.ProductID = '10238687' OR yAP.ProductID = '10238688')
)
)
SELECT * INTO tbl_Difference FROM differ
Anyway to make this faster?

Answer 1

Can you filter the 2 large tables before you try to join them using AND filter in your where?
WITH tAPcte AS
(
SELECT * -- fields you need
FROM tbl_Prices
WHERE ProductID IN ('10238610',
'10238620',
'10238621',
'10238687',
'10238688')
),
yAPcte AS
(
SELECT * -- fields you need
FROM tbl_Prices_Yesterday
WHERE ProductID IN ('10238610',
'10238620',
'10238621',
'10238687',
'10238688')
)
differ AS
(
SELECT
tAP.CustomerID, tAP.ProductID, yAP.CustomerID AS 'Yest_CustomerID', yAP.ProductID AS 'Yest_ProductID',
tAP.PDG, tAP.DiscPct1, tAP.DiscPct2,
yAP.DiscPct1 AS 'Yest_DiscPct1',
yAP.DiscPct2 AS 'Yest_DiscPct2',
CONVERT(DECIMAL(18,2),tAP.DiscPct1 - yAP.DiscPct1) AS 'DiscPct1_Difference',
CONVERT(DECIMAL(18,2),tAP.DiscPct2 - yAP.DiscPct2) AS 'DiscPct2_Difference',
tAP.internalSPANumber, yAP.internalSPANumber AS 'Yest_InternalSPANumber', tAP.SPAUniqueReference,
tAP.Project,
tAP.ExpiryDate,tAP.Subaddress, tAP.PriceType, yAP.PriceType AS 'Yest_PriceType', tAP.ListPrice,
tAP.NettPrice, yAP.NettPrice AS 'Yest_NettPrice',
CONVERT(DECIMAL(18,2),tAP.NettPrice- yAP.NettPrice) AS 'NettPrice_Difference'
FROM tAPcte tAP FULL OUTER JOIN yAPcte yAP ON tAP.CustomerId = yAP.CustomerID AND tAP.ProductID = yAP.ProductID
AND tAP.PDG = yAP.PDG AND tAP.Project = yAP.Project AND tAP.PriceType = yAP.PriceType
WHERE (((tAP.DiscPct1 <> yAP.DiscPct1)
OR (tAP.DiscPct2 <> yAP.DiscPct2)
OR (yAP.CustomerID IS NULL)
OR (tAP.CustomerID IS NULL)
OR (tAP.NettPrice <> yAP.NettPrice)
OR (tAP.InternalSPANumber <> yAP.InternalSPANumber))
)
SELECT * INTO tbl_Difference FROM differ