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  1. #1
    Join Date
    Feb 2004
    Location
    Burbank & Santa Cruz de la Sierra
    Posts
    3,716

    Question Unanswered: smalldatetime comparison between local server and linked server fails?

    Hi all,

    I have the following select that is designed to compare values on parallel servers.
    Code:
    SELECT TA1.EPS, TA1.Sales, TA1.Income, TA1.EarningsReportDate,TA2.EPS, TA2.Sales, TA2.Income, TA2.EarningsReportDate
    	FROM 		TradeAnalysis.dbo.SalesIncome_Quarterly AS TA1
    	FULL OUTER JOIN L_TA_MIRROR.TradeAnalysis.dbo.SalesIncome_Quarterly AS TA2
    	      	ON 	((TA1.OSID = TA2.OSID) AND (TA1.QtrYear = TA2.QtrYear) AND (TA1.QuarterNo = TA2.QuarterNo))
    	WHERE		(BINARY_CHECKSUM(TA1.EPS, TA1.Sales, TA1.Income, TA1.EarningsReportDate) <>
    			BINARY_CHECKSUM(TA2.EPS, TA2.Sales, TA2.Income, TA2.EarningsReportDate))
    Disregard the full outer join, it is necessary in the full select, I have just pared it down to show here and for testing. A standard join will also have the same result.

    The trouble is that the comparison (the BINARY_CHECKSUM) is failing on the EarningsReportDate column, which is defined on BOTH servers in DUPLICATE databases as a smalldatetime.

    The data is actually the same in both rows of each table (as is all the other data being compared). What I am seeing is that the select returns milliseconds on the LINKED server (the L_TA_MIRROR reference), but not on the local database?

    for example,
    Local server data returned in above select is 2000-01-28 00:00:00
    Linked server data returned in above select is 2000-01-28 00:00:00.000

    Wassup with THAT? If I remove the date from the select/comparison, it says everything matches, so I am pretty sure this is the culprit that is causing the BINARY_CHECKSUM comparison to fail.

    Is there some setting that I need to put on the Linked Server reference that says "treat this as the smalldatetime data type it IS, dammit!"????

    I can get by the issue if I replace the date reference in the linked server part of the select with CAST(TA2.EarningsReportDate AS smalldatetime) but why do I have to do this?

    Yes, I am SURE both servers have the column in question defined as a smalldatetime, as running the same select on either server causes the same failure, but only when referencing the LINKED server column.
    aka "Paul"
    Non est ei similis.

    I just read "100 Things To Do Before You Die". I was surprised that "Yell for help!!" wasn't one of them

  2. #2
    Join Date
    Feb 2004
    Location
    Burbank & Santa Cruz de la Sierra
    Posts
    3,716
    From BOL, it appears that pulling data from a linked server actually causes the remote date data to be converticated (yes, a very technical term ) to a DATETIME format, even if it is defined on the remote server as a SMALLDATETIME.

    Seems like there has GOT to be some server setting that one can use to prevent this, or perhaps creating the linked server with a Provider Name as something other than a "Microsoft OLE DB Provider for SQL Server", that will get around this.

    I haven't yet found a DIRECT reference in BOL to this behavior, but have discovered a few indirect suggestions which seem to support my interpretation of the behaviour.

    FYI, the linked server is created in our system so that we can use it as an OLEDB "alias" to allow the use of a standardized stored procedure portable among different servers and databases. That's why we can't use a "standard" linked server reference to a remote server, and probably also is a key to the behavior I am seeing.

    Anyway, thanks for burning what might be at least a cursory number of brain cells to view and read the issue, even if no suggestions were readily apparent. I do appreciate it, and until I can figure out a way around it, I'll use my CAST() workaround (which really chaps my drawers, BTW )
    aka "Paul"
    Non est ei similis.

    I just read "100 Things To Do Before You Die". I was surprised that "Yell for help!!" wasn't one of them

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