(SQL Server) Decompress Large Binary File in Blocks

Decompresses a large binary file in blocks. This example uses BeginDecompressBytes, MoreDecompressBytes, and EndDecompressBytes.

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
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

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

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

    -- Open a previously compressed file for decompressing.
    -- See Compress Large File in Blocks

    DECLARE @success int
    EXEC sp_OAMethod @facSrc, 'OpenForRead', @success OUT, 'qa_data/bmp/compressedBmp.dat'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @facSrc, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @facSrc
        EXEC @hr = sp_OADestroy @facDest
        RETURN
      END

    -- If we compress in 32K chunks, find out how many blocks there will be.
    DECLARE @blockSize int
    SELECT @blockSize = 32768
    DECLARE @numBlocks int
    EXEC sp_OAMethod @facSrc, 'GetNumBlocks', @numBlocks OUT, @blockSize

    -- Open an output file for the decompressed data.
    EXEC sp_OAMethod @facDest, 'OpenForWrite', @success OUT, 'qa_output/decompressed.bmp'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @facDest, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @facSrc
        EXEC @hr = sp_OADestroy @facDest
        RETURN
      END

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

    EXEC sp_OASetProperty @compress, 'Algorithm', 'deflate'

    DECLARE @i int
    SELECT @i = 0
    WHILE @i < @numBlocks
      BEGIN
        EXEC sp_OAMethod @facSrc, 'ReadBlock', @compressedBytes OUT, @i, @blockSize
        IF @i = 0
          BEGIN
            EXEC sp_OAMethod @compress, 'BeginDecompressBytes', @decompressedBytes OUT, @compressedBytes
          END
        ELSE
          BEGIN
            EXEC sp_OAMethod @compress, 'MoreDecompressBytes', @decompressedBytes OUT, @compressedBytes
          END

        EXEC sp_OAMethod @facDest, 'FileWrite', @success OUT, @decompressedBytes

        SELECT @i = @i + 1
      END

    -- At the very end, flush any remaining decompressed bytes, if any.
    EXEC sp_OAMethod @compress, 'EndDecompressBytes', @decompressedBytes OUT
    EXEC sp_OAMethod @facDest, 'FileWrite', @success OUT, @decompressedBytes

    EXEC sp_OAMethod @facSrc, 'FileClose', NULL
    EXEC sp_OAMethod @facDest, 'FileClose', NULL


    PRINT 'Finished decompressing file.'

    EXEC @hr = sp_OADestroy @facSrc
    EXEC @hr = sp_OADestroy @facDest
    EXEC @hr = sp_OADestroy @compress


END
GO