SQL join hints affect row count?

Question

I have an SQL view on SQL 2016 SP2 that joins on 14 tables with no predicate.

                WHEN dsp.DimSourceSystemID=2 THEN edsp.CyberExposureGroup
                WHEN dsp.DimSourceSystemID=4 THEN vdsp.CyberExposureGroup
                ELSE 'Unknown' END AS CyberExposureGroup    
       FROM     dwh.DimPolicy dsp
                INNER JOIN Eclipse.DimPolicyExt edsp
                ON dsp.DimEclipsePolicyExtID = edsp.DimEclipsePolicyExtID
                INNER JOIN Velocity.DimPolicyExt vdsp
                ON dsp.DimVelocityPolicyExtID = vdsp.DimVelocityPolicyExtID
                INNER JOIN DWH.DimProgramme dp
                ON dsp.DimProgrammeID = dp.DimProgrammeID
                INNER JOIN DWH.DimPricingLeaderStatus dpls
                ON edsp.DimPricingLeaderStatusID = dpls.DimPricingLeaderStatusID
                INNER JOIN DWH.DimPlacingBasis dpb
                ON dsp.DimPlacingBasisID = dpb.DimPlacingBasisID
                INNER JOIN DWH.DimCoverageBasis dcb
                ON dsp.DimCoverageBasisID = dcb.DimCoverageBasisID
            --INNER JOIN DWH.DimNewRenewed dnr
            --  ON dsp.DimNewRenewedID = dnr.DimNewRenewedID
                INNER JOIN DWH.DimSubClass dsc
                ON edsp.DimSubClassID = dsc.DimSubClassID
                INNER JOIN DWH.DimStatsMinorClass dsminc
                ON edsp.DimStatsMinorClassID = dsminc.DimStatsMinorClassID
                INNER JOIN DWH.DimStatsMajorClass dsmajc
                ON edsp.DimStatsMajorClassID = dsmajc.DimStatsMajorClassID
                ----------------------R5--------------------------
                INNER JOIN DWH.DimCoverholder cv
                ON edsp.DimCoverholderID = cv.DimCoverholderID
            ----------------------R7--------------------------
                LEFT JOIN dwh.DimPlacingBasis MDPB
                ON MDPB.MasterDataPlacingBasis = edsp.MasterPlacingBasis
                INNER JOIN DWH.DimAssured da
                ON dsp.DimAssuredID = da.DimAssuredID
                --Underwriter Information R15
                INNER JOIN DWH.DimUnderwriter duw
                ON dsp.DimUnderwriterID = duw.DimUnderwriterID

I want to use the loop join hint so that the query will have less parallelism overhead.

                WHEN dsp.DimSourceSystemID=2 THEN edsp.CyberExposureGroup
                WHEN dsp.DimSourceSystemID=4 THEN vdsp.CyberExposureGroup
                ELSE 'Unknown' END AS CyberExposureGroup    
       FROM     dwh.DimPolicy dsp
                INNER LOOP JOIN Eclipse.DimPolicyExt edsp
                ON dsp.DimEclipsePolicyExtID = edsp.DimEclipsePolicyExtID
                INNER LOOP JOIN Velocity.DimPolicyExt vdsp
                ON dsp.DimVelocityPolicyExtID = vdsp.DimVelocityPolicyExtID
                INNER LOOP JOIN DWH.DimProgramme dp
                ON dsp.DimProgrammeID = dp.DimProgrammeID
                INNER LOOP JOIN DWH.DimPricingLeaderStatus dpls
                ON edsp.DimPricingLeaderStatusID = dpls.DimPricingLeaderStatusID
                INNER LOOP JOIN DWH.DimPlacingBasis dpb
                ON dsp.DimPlacingBasisID = dpb.DimPlacingBasisID
                INNER LOOP JOIN DWH.DimCoverageBasis dcb
                ON dsp.DimCoverageBasisID = dcb.DimCoverageBasisID
            --INNER JOIN DWH.DimNewRenewed dnr
            --  ON dsp.DimNewRenewedID = dnr.DimNewRenewedID
                INNER LOOP JOIN DWH.DimSubClass dsc
                ON edsp.DimSubClassID = dsc.DimSubClassID
                INNER LOOP JOIN DWH.DimStatsMinorClass dsminc
                ON edsp.DimStatsMinorClassID = dsminc.DimStatsMinorClassID
                INNER LOOP JOIN DWH.DimStatsMajorClass dsmajc
                ON edsp.DimStatsMajorClassID = dsmajc.DimStatsMajorClassID
                ----------------------R5--------------------------
                INNER LOOP JOIN DWH.DimCoverholder cv
                ON edsp.DimCoverholderID = cv.DimCoverholderID
            ----------------------R7--------------------------
                LEFT LOOP JOIN dwh.DimPlacingBasis MDPB
                ON MDPB.MasterDataPlacingBasis = edsp.MasterPlacingBasis
                INNER LOOP JOIN DWH.DimAssured da
                ON dsp.DimAssuredID = da.DimAssuredID
                --Underwriter Information R15
                INNER LOOP JOIN DWH.DimUnderwriter duw
                ON dsp.DimUnderwriterID = duw.DimUnderwriterID

This works and the query runs faster at the expense of more IO, however to my surprise I get slightly different row counts for the two different versions of the view. 7,877,287 rows compared to 7,877,285 rows. This is a data warehouse but there are no inserts going on. So do join hints affect the overall number of rows or could this be a bug?

Answer 1

ok, I've actually worked out what the problem is myself - it a bug in SSMS! I'm using SSMS 18.6 and the number of rows showed bottom right is incorrect. If you actually look at the number of rows in the results tab, then they do correspond, that is to say join hints do not make a difference, which makes sense