SQL Server

SFTP Upload Large File in Parts

See more SFTP Examples

Demonstrates how to split a large file into N parts and then upload each part separately. This technique can be used to potentially avoid limits a SFTP server might impose on upload file size. SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    -- This example assumes the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @sftp int
    EXEC @hr = sp_OACreate 'Chilkat.SFtp', @sftp OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Set some timeouts, in milliseconds:
    EXEC sp_OASetProperty @sftp, 'ConnectTimeoutMs', 5000
    EXEC sp_OASetProperty @sftp, 'IdleTimeoutMs', 10000

    -- Connect to the SSH server.  
    -- The standard SSH port = 22
    -- The hostname may be a hostname or IP address.
    DECLARE @hostname nvarchar(4000)
    SELECT @hostname = 'sftp.example.com'
    DECLARE @port int
    SELECT @port = 22
    EXEC sp_OAMethod @sftp, 'Connect', @success OUT, @hostname, @port
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @sftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sftp
        RETURN
      END

    -- Authenticate with the SSH server.  Chilkat SFTP supports
    -- both password-based authenication as well as public-key
    -- authentication.  This example uses password authenication.
    EXEC sp_OAMethod @sftp, 'AuthenticatePw', @success OUT, 'myLogin', 'myPassword'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @sftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sftp
        RETURN
      END

    -- After authenticating, the SFTP subsystem must be initialized:
    EXEC sp_OAMethod @sftp, 'InitializeSftp', @success OUT
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @sftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sftp
        RETURN
      END

    -- Open a remote file for writing on the SSH server.
    -- If the file already exists, it is overwritten.
    -- (Specify "createNew" instead of "createTruncate" to
    -- prevent overwriting existing files.)
    DECLARE @handle nvarchar(4000)
    EXEC sp_OAMethod @sftp, 'OpenFile', @handle OUT, 'big.zip', 'writeOnly', 'createTruncate'
    EXEC sp_OAGetProperty @sftp, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 <> 1
      BEGIN
        EXEC sp_OAGetProperty @sftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sftp
        RETURN
      END

    -- We're going to upload the local file "qa_data/zips/big.zip" (a relative local path from our current working directory)
    -- to the SFTP server.
    DECLARE @localFilePath nvarchar(4000)
    SELECT @localFilePath = 'qa_data/zips/big.zip'

    -- Rather than uploading in one shot, we'll read the local file in chunks
    -- and upload a chunk at a time.
    DECLARE @fac int
    EXEC @hr = sp_OACreate 'Chilkat.FileAccess', @fac OUT

    EXEC sp_OAMethod @fac, 'OpenForRead', @success OUT, @localFilePath
    IF @success = 0
      BEGIN
        EXEC sp_OAMethod @sftp, 'CloseHandle', @success OUT, @handle
        EXEC sp_OAGetProperty @fac, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sftp
        EXEC @hr = sp_OADestroy @fac
        RETURN
      END

    -- If we were to split the local file into 128K chunks, how many chunks (blocks) would
    -- we have, including the last partial block?
    DECLARE @blockSize int
    SELECT @blockSize = 131072
    DECLARE @numBlocks int
    EXEC sp_OAMethod @fac, 'GetNumBlocks', @numBlocks OUT, @blockSize

    PRINT 'Number of blocks = ' + @numBlocks

    DECLARE @bd int
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bd OUT

    DECLARE @i int
    SELECT @i = 0
    WHILE @i < @numBlocks
      BEGIN
        -- Read the Nth block, which gets appended to the bd.  (which means
        -- we must clear the contents of bd before the next iteration)
        EXEC sp_OAMethod @fac, 'ReadBlockBd', @success OUT, @i, @blockSize, @bd
        IF @success = 0
          BEGIN
            EXEC sp_OAMethod @sftp, 'CloseHandle', @success OUT, @handle
            EXEC sp_OAGetProperty @fac, 'LastErrorText', @sTmp0 OUT
            PRINT @sTmp0
            EXEC @hr = sp_OADestroy @sftp
            EXEC @hr = sp_OADestroy @fac
            EXEC @hr = sp_OADestroy @bd
            RETURN
          END

        -- Upload this block to the open remote file.
        EXEC sp_OAMethod @sftp, 'WriteFileBd', @success OUT, @handle, @bd
        IF @success = 0
          BEGIN
            EXEC sp_OAGetProperty @sftp, 'LastErrorText', @sTmp0 OUT
            PRINT @sTmp0
            EXEC @hr = sp_OADestroy @sftp
            EXEC @hr = sp_OADestroy @fac
            EXEC @hr = sp_OADestroy @bd
            RETURN
          END

        -- Clear the contents for the next iteration.
        EXEC sp_OAMethod @bd, 'Clear', @success OUT

        SELECT @i = @i + 1
      END

    -- Close the local file.
    EXEC sp_OAMethod @fac, 'FileClose', NULL

    -- -----------------------------------------------------------------------------
    -- This is important.  You must close the handle on the server.
    -- Otherwise open handles will accumulate on the server until eventually a limit
    -- is reached and the server will fail on a call to OpenFile.
    -- -----------------------------------------------------------------------------

    -- Close the remote file handle on the server.
    EXEC sp_OAMethod @sftp, 'CloseHandle', @success OUT, @handle
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @sftp, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sftp
        EXEC @hr = sp_OADestroy @fac
        EXEC @hr = sp_OADestroy @bd
        RETURN
      END


    PRINT 'Success.'

    EXEC @hr = sp_OADestroy @sftp
    EXEC @hr = sp_OADestroy @fac
    EXEC @hr = sp_OADestroy @bd


END
GO