(SQL Server) Unzip Binary File to Stream

Demonstrates how to unzip a large binary file to a stream to allow the application to process the uncompressed bytes chunk by chunk.

Note: This example requires Chilkat v9.5.0.67 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- 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)
    -- This requires the Chilkat Zip API to have been previously unlocked.
    -- See Unlock Chilkat Zip for sample code.

    DECLARE @zip int
    -- Use "Chilkat_9_5_0.Zip" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Zip', @zip OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- First open a .zip.
    DECLARE @success int
    EXEC sp_OAMethod @zip, 'OpenZip', @success OUT, 'qa_data/zips/big.zip'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @zip, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @zip
        RETURN
      END

    -- Get the entry to be unzipped to a stream..
    DECLARE @entry int
    EXEC sp_OAMethod @zip, 'GetEntryByIndex', @entry OUT, 0
    EXEC sp_OAGetProperty @zip, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 <> 1
      BEGIN
        EXEC sp_OAGetProperty @zip, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @zip
        RETURN
      END

    DECLARE @dataStream int
    -- Use "Chilkat_9_5_0.Stream" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Stream', @dataStream OUT

    DECLARE @unzipTask int
    EXEC sp_OAMethod @entry, 'UnzipToStreamAsync', @unzipTask OUT, @dataStream
    EXEC sp_OAGetProperty @entry, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 <> 1
      BEGIN
        EXEC sp_OAGetProperty @entry, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @entry

        EXEC @hr = sp_OADestroy @zip
        EXEC @hr = sp_OADestroy @dataStream
        RETURN
      END

    -- Start the background unzip thread.
    EXEC sp_OAMethod @unzipTask, 'Run', @success OUT

    -- We'll read the uncompressed data chunk-by-chunk and write to an output file.
    DECLARE @fac int
    -- Use "Chilkat_9_5_0.FileAccess" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.FileAccess', @fac OUT

    EXEC sp_OAMethod @fac, 'OpenForWrite', @success OUT, 'qa_output/out.dat'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @fac, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @entry

        EXEC @hr = sp_OADestroy @zip
        EXEC @hr = sp_OADestroy @dataStream
        EXEC @hr = sp_OADestroy @fac
        RETURN
      END

    -- Read the stream.  (this is reading the unzipped file data)
    DECLARE @bd int
    -- Use "Chilkat_9_5_0.BinData" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @bd OUT

    EXEC sp_OAGetProperty @dataStream, 'EndOfStream', @iTmp0 OUT
    WHILE @iTmp0 <> 1
      BEGIN
        -- Get the next chunk of decompressed bytes.
        EXEC sp_OAMethod @dataStream, 'ReadBd', @success OUT, @bd
        -- Do something with it..
        -- In this simple example, we'll just write to the file.
        EXEC sp_OAMethod @fac, 'FileWriteBd', @success OUT, @bd, 0, 0
        -- Clear for the next read.
        EXEC sp_OAMethod @bd, 'Clear', @success OUT
      END

    EXEC sp_OAMethod @fac, 'FileClose', NULL

    EXEC @hr = sp_OADestroy @entry

    EXEC @hr = sp_OADestroy @unzipTask


    PRINT 'Success.'

    EXEC @hr = sp_OADestroy @zip
    EXEC @hr = sp_OADestroy @dataStream
    EXEC @hr = sp_OADestroy @fac
    EXEC @hr = sp_OADestroy @bd


END
GO