Linked Server Insert-Select Performance

Question

Assume that I have a table on my local which is Local_Table and I have another server and another db and table, which is Remote_Table (table struct

Answer 1

If you must push data from the source to the target (e.g., for firewall or other permissions reasons), you can do the following:

In the source database, convert the recordset to a single XML string (i.e., multiple rows and columns combined into a single XML string). Then push that XML over as a single row (as a varchar(max), since XML isn't allowed over linked databases in SQL Server).

    DECLARE @xml XML

    SET @xml = (select * from SourceTable FOR XML path('row'))

    Insert into TempTargetTable values (cast(@xml AS VARCHAR(max)))

In the target database, cast the varchar(max) as XML and then use XML parsing to turn that single row and column back into a normal recordset.

DECLARE @X XML = (select '' + ImportString + '' from TempTargetTable)

DECLARE @iX INT
EXEC sp_xml_preparedocument @ix output, @x

insert into TargetTable
SELECT [col1],
       [col2]
FROM OPENXML(@iX, '//row', 2) 
WITH ([col1] [int],
       [col2] [varchar](128)
)

EXEC sp_xml_removedocument @iX