Intermittent issue with outer joins on subqueries

Hello, we are running into an issue which seems to be a bug in the way
MSSQL joins on subqueries. The below query is run daily by a scheduled
task and usually runs correctly. About once a week the query produces
a resultset that makes it appear that the outer join on the subquery
(alias: POINFO) was changed to an inner join. The resultset has only a
percentage of the records it should have as a result. Are there any
know issues with MSSQL 2000 SP4 that are know to cause this. BTW, the
problem happens on a Win2000 server. Thanks.
SELECT *
FROM rc.dbo.LineItems LI
INNER JOIN rc.dbo.orders O
ON O.guidPK = LI.orderguidPK
INNER JOIN decode DECODE
ON O.status = DECODE.status
INNER JOIN products P
ON LI.productPK = P.PK
/* The below join periodically seems to become an inner join
*/
LEFT OUTER JOIN (SELECT PO.OrderNumber, FP.ProductNumber
from purchase_orders PO
INNER JOIN purchase_orders_lines POL
ON PO.PK = POL.purchaseorderPK
INNER JOIN fulfillment_products FP
ON POL.intProductID = FP.PK AND PO.supplierPK = FP.supplierPK
INNER JOIN I18NManufacturer MAN
ON FP.manPK = MAN.PK
INNER JOIN suppliers S
ON FP.supplierPK = SM.PK
WHERE PO.status <>9 AND MAN.locale = 1041) AS POINFO
ON O.order_number = POINFO.order_number AND LI.productPK =
POINFO.productPK
WHERE O.order_type <> 1 and O.active=1
and O.status between 2 and 32
Can you capture the plan when the bad result happens, and compare it to the
normal plan?
(In other words, does it happen frequently enough that if you tried, you
could reproduce the problem in Query Analyzer?)
"Jesse Hogan" <JesseHogan0@.gmail.com> wrote in message
news:049ac85e-1cde-4fd9-8755-0b03494302d2@.1g2000hsl.googlegroups.com...
> Hello, we are running into an issue which seems to be a bug in the way
> MSSQL joins on subqueries. The below query is run daily by a scheduled
> task and usually runs correctly. About once a week the query produces
> a resultset that makes it appear that the outer join on the subquery
> (alias: POINFO) was changed to an inner join. The resultset has only a
> percentage of the records it should have as a result. Are there any
> know issues with MSSQL 2000 SP4 that are know to cause this. BTW, the
> problem happens on a Win2000 server. Thanks.
> SELECT *
> FROM rc.dbo.LineItems LI
> INNER JOIN rc.dbo.orders O
> ON O.guidPK = LI.orderguidPK
> INNER JOIN decode DECODE
> ON O.status = DECODE.status
> INNER JOIN products P
> ON LI.productPK = P.PK
> /* The below join periodically seems to become an inner join
> */
> LEFT OUTER JOIN (SELECT PO.OrderNumber, FP.ProductNumber
> from purchase_orders PO
> INNER JOIN purchase_orders_lines POL
> ON PO.PK = POL.purchaseorderPK
> INNER JOIN fulfillment_products FP
> ON POL.intProductID = FP.PK AND PO.supplierPK = FP.supplierPK
> INNER JOIN I18NManufacturer MAN
> ON FP.manPK = MAN.PK
> INNER JOIN suppliers S
> ON FP.supplierPK = SM.PK
> WHERE PO.status <>9 AND MAN.locale = 1041) AS POINFO
> ON O.order_number = POINFO.order_number AND LI.productPK =
> POINFO.productPK
> WHERE O.order_type <> 1 and O.active=1
> and O.status between 2 and 32
|||I would be much more likely to think the WHERE clause is limiting the rows
'unexpectedly'. Perhaps you should set up an audit trail whereby you store
the COUNT(*) of the entire SELECT as well as the COUNT(*) for the SELECT
without the join to POINFO by itself into a table each time this process is
run (with enough identifying information added to ensure you can pinpoint
the rows for each run). This will help you see if you are affecting fewer
rows with the main query simply because of the WHERE clause or is the LOJ
magically translating into an INNER JOIN. That will give you definitive
evidence to take to Microsoft if it is a bug too (which I will definitely
admit isn't out of the question). :-)
Doing a quick check of post-SP4 hotfixes, see if this one applies
http://support.microsoft.com/kb/892310/
Kevin G. Boles
Indicium Resources, Inc.
SQL Server MVP
kgboles a earthlink dt net
"Jesse Hogan" <JesseHogan0@.gmail.com> wrote in message
news:049ac85e-1cde-4fd9-8755-0b03494302d2@.1g2000hsl.googlegroups.com...
> Hello, we are running into an issue which seems to be a bug in the way
> MSSQL joins on subqueries. The below query is run daily by a scheduled
> task and usually runs correctly. About once a week the query produces
> a resultset that makes it appear that the outer join on the subquery
> (alias: POINFO) was changed to an inner join. The resultset has only a
> percentage of the records it should have as a result. Are there any
> know issues with MSSQL 2000 SP4 that are know to cause this. BTW, the
> problem happens on a Win2000 server. Thanks.
> SELECT *
> FROM rc.dbo.LineItems LI
> INNER JOIN rc.dbo.orders O
> ON O.guidPK = LI.orderguidPK
> INNER JOIN decode DECODE
> ON O.status = DECODE.status
> INNER JOIN products P
> ON LI.productPK = P.PK
> /* The below join periodically seems to become an inner join
> */
> LEFT OUTER JOIN (SELECT PO.OrderNumber, FP.ProductNumber
> from purchase_orders PO
> INNER JOIN purchase_orders_lines POL
> ON PO.PK = POL.purchaseorderPK
> INNER JOIN fulfillment_products FP
> ON POL.intProductID = FP.PK AND PO.supplierPK = FP.supplierPK
> INNER JOIN I18NManufacturer MAN
> ON FP.manPK = MAN.PK
> INNER JOIN suppliers S
> ON FP.supplierPK = SM.PK
> WHERE PO.status <>9 AND MAN.locale = 1041) AS POINFO
> ON O.order_number = POINFO.order_number AND LI.productPK =
> POINFO.productPK
> WHERE O.order_type <> 1 and O.active=1
> and O.status between 2 and 32