SQL View slow to run - sql

Question

I have the following SQL statement but it takes 20 seconds to run, how can I make it faster ?
SELECT TOP (100) PERCENT
dbo.pod.order_no,
dbo.pod.order_line_no,
dbo.poh.currency,
dbo.pod.warehouse,
dbo.pod.product,
dbo.poh.address1,
dbo.pod.description,
dbo.pod.date_required,
dbo.pod.qty_ordered,
dbo.pod.qty_received,
dbo.pod.qty_invoiced,
dbo.pod.status,
dbo.poh.date_entered,
dbo.stock.analysis_c,
dbo.stock.catalogue_number,
dbo.stock.drawing_number,
dbo.poh.date_required AS OriginalRequiredDate,
dbo.stock.standard_cost,
dbo.poh.supplier_ref,
dbo.stock.reorder_days,
dbo.pod.local_expect_cost,
dbo.poh.supplier,
dbo.pod.qty_ordered - dbo.pod.qty_received AS qty_outstanding,
dbo.stock.warehouse AS warehouse2
FROM dbo.stock
RIGHT OUTER JOIN dbo.pod
ON dbo.stock.product = dbo.pod.product
LEFT OUTER JOIN dbo.poh
ON dbo.pod.order_no = dbo.poh.order_no
WHERE (dbo.pod.status <> 'C')
AND (dbo.poh.status <> '9')
AND (dbo.stock.analysis_c IN ('FB', 'FP', 'RM', '[PK]'))
AND (dbo.pod.qty_ordered - dbo.pod.qty_received > 0)
AND (dbo.stock.warehouse = 'FH')
The execution plan says remote Query taking up 89% - These tables are located through a linked server.

Answer 1

I'd move the (dbo.stock.warehouse = 'FH') up the where clause to be the first item in the where clause since this is your main table. I'd then run the query through query profiler to see where the lag is, this might help narrow the area that needs to change

Answer 2

As in comments, there shouldn't be any TOP statement (what keeps putting it automatically?).
I'd rewrite your view like that (for readability):
SELECT P.order_no
, P.order_line_no
, T.currency
, P.warehouse
, P.product
, T.address1
, P.[Description]
, P.date_required
, P.qty_ordered
, P.qty_received
, P.qty_invoiced
, P.[Status]
, T.date_entered
, S.analysis_c
, S.catalogue_number
, S.drawing_number
, T.date_required AS OriginalRequiredDate
, S.standard_cost
, T.supplier_ref
, S.reorder_days
, P.local_expect_cost
, T.supplier
, P.qty_ordered - P.qty_received AS qty_outstanding
, S.warehouse AS warehouse2
FROM dbo.stock AS S
RIGHT JOIN dbo.pod AS P
ON S.product = P.product
LEFT JOIN dbo.poh AS T
ON P.order_no = T.order_no
WHERE P.[Status] <> 'C'
AND T.[Status] <> '9'
AND S.analysis_c IN ('FB', 'FP', 'RM', '[PK]')
AND P.qty_ordered - P.qty_received > 0
AND S.warehouse = 'FH';
Also, I'd create following indexes, which should increase performance (hopefully I didn't miss any columns):
CREATE NONCLUSTERED INDEX idx_Stock_product_warehouse_analysisC_iColumns
ON dbo.Stock (product, warehouse, analysis_c)
INCLUDE (catalogue_number, drawing_number, standard_cost, reorder_days);
CREATE NONCLUSTERED INDEX idx_Pod_product_orderNo_status_qtyOrdered_qtyReceived_iColumns
ON dbo.Pod (product, order_no, [status], qty_ordered, qty_received)
INCLUDE (order_line_no, warehouse, [Description], date_required, qty_invoiced, [status], local_expect_cost);
CREATE NONCLUSTERED INDEX idx_Poh_orderNo_Status_iColumns
ON dbo.Poh (order_no, [Status])
INCLUDE (currency, address1, date_entered, date_required, supplier_ref, supplier);

Answer 3

Since there isn't really much to work on, just general guesses that what could help. You have 5 criteria in your SQL that could help to reduce the amount of rows:
pod.status <> 'C'
pod.qty_ordered - pod.qty_received > 0
poh.status <> '9'
stock.analysis_c IN ('FB', 'FP', 'RM', '[PK]')
stock.warehouse = 'FH'
For each of these the selectivity of the criteria is essential. For example if 90% of your rows have pod.status C, then you should probably add a filtered index for status <> 'C' (and same thing with poh.status field too).
For stock table warehouse (and analysis_c): If the given criteria limits the data a lot, adding index to the field should help.
if pod.qty_ordered is usually less or equal to pod.qty_received, it might be a good idea to add a computed persistent column and index that and use it in the where clause.
Since these fields are in different tables, the query should start from the one that limits the data most, so you might want to index that table only, the others might not help at all. Also I assume you have already indexes for the fields you're joining the tables with. If not, that's the first thing to look at. Always when adding new indexes, it of course has a (small) impact on inserts / updates.
If the query does a lot of key lookups, it might be help if you add all the other columns from that table as included columns into the index, but that also has a impact on updates / inserts.