Sql-server – Getting error “String or binary data would be truncated” even for ‘text’ data type

Eventually found the answer when attempting to work around the problem using SSIS and the VFP ODBC driver. VFPODBC provided a more verbose error message, stating that the .fpt file was missing for the dbf file I was attempting to query.

The staff that did the original data copy (the VFP data is hosted off server) failed to include all the data available (.cdxs, .fpts, .etc). After recopying the data, the linked server described above functions correctly.

I insert into this table small amount of data just about 1000 rows and it takes more than 4 minutes

Remote data modifications through a linked server use the sp_cursor model. The effect is similar to issuing 1000 separate single inserts (one for each row). If a round trip takes 250ms, 1000 such trips will take 4 minutes and 10 seconds. Using a bulk loading method such as bcp or SSIS will generally be more efficient (unless the number of rows to be inserted is tiny).

Another alternative for ad-hoc needs is to build a string containing a single INSERT statement with multiple rows in the VALUES clause. The statement is then used with EXECUTE AT, for example:

-- Note local-to-azure table name used, not four-part syntax
DECLARE @sql varchar(max) = 'INSERT dbo.Test VALUES ';

-- Build a list of 1000 numbers to insert    
SELECT @sql += '(' + CONVERT(varchar(11), n) + '),'
FROM dbo.Numbers AS N
WHERE n BETWEEN 1 AND 1000;

-- Remove trailing comma
SET @sql = LEFT(@sql, LEN(@sql) - 1);

-- For debugging
PRINT @sql;

-- Execute the finished statement at the remote server;
EXECUTE (@sql) AT AZURE;

The constructed insert statement executes at the Azure database, so a local name is used for the table (note: building a dynamic insert statement using a four-part target name buys you nothing).

Note that EXECUTE ... AT requires RPC and RPC OUT enabled in the linked server options.

The VALUES clause for a plan INSERT statement is limited to 1000 elements. There are ways around that (a VALUES clause in a CTE does not have that restriction). You could also choose to build 1000-row batches or build single-row insert statements, but if the there is that much data on a regular basis, you would probably be better off using one of the bulk loading methods instead.