Kevin Crosbie wrote:
> DA Morgan wrote:
>
>>Thanks. But where is the file you want compressed?
>
>
> Well, actually I just wanted to see how the raw text I had set up in the
> script compressed, but a large text file is a good idea too as we won't
> be led astray by compression header information etc.
>
> I downloaded the following file into my /tmp folder:
> wget http://www.gutenberg.org/files/18637/18637-8.txt
>
> It should be quite compressible as it's not got much real information. ;)
>
> If you set up a user directory as (Given proper permissions etc.):
> create or replace directory OS_TMP_DIR as '/tmp';
>
> Then run:
>
> set serveroutput on
>
> DECLARE
> rawtext raw(32767);
> uncompressed blob;
> compressed1 blob;
> compressed2 blob;
> uncompressed1 blob;
> uncompressed2 blob;
> v_text_file bfile := bfilename('OS_TMP_DIR', '18637-8.txt');
> v_length number;
> v_dest_offset number := 1;
> v_src_offset number := 1;
> BEGIN
>
> dbms_lob.createtemporary(uncompressed, TRUE);
> dbms_lob.open(uncompressed, dbms_lob.lob_readwrite);
>
> v_length := dbms_lob.getlength(v_text_file);
> dbms_lob.fileopen (
> file_loc => v_text_file,
> open_mode => dbms_lob.file_readonly);
>
> dbms_lob.loadblobfromfile (
> dest_lob => uncompressed,
> src_bfile => v_text_file,
> amount => v_length,
> dest_offset => v_dest_offset,
> src_offset => v_src_offset);
>
> dbms_lob.close (file_loc => v_text_file);
>
> dbms_output.put_line('Uncompressed Length: '
> || dbms_lob.getlength(uncompressed));
>
> compressed1 := compressor.blob_compress(uncompressed);
>
> dbms_output.put_line('Java Compressed Length: '
> || dbms_lob.getlength(compressed1));
>
> compressed2 := utl_compress.lz_compress(uncompressed);
>
> dbms_output.put_line('UTL Compressed Length: '
> || dbms_lob.getlength(compressed2));
>
> uncompressed1 := compressor.blob_decompress(compressed1);
>
> dbms_output.put_line('Java Decompressed Length: '
> || dbms_lob.getlength(uncompressed1));
>
> uncompressed2 := utl_compress.lz_uncompress(compressed2);
>
> dbms_output.put_line('UTL Uncompressed Length: '
> || dbms_lob.getlength(uncompressed2));
>
> dbms_lob.freetemporary(uncompressed1);
> dbms_lob.freetemporary(uncompressed2);
>
> BEGIN
> uncompressed1 := compressor.blob_decompress(compressed2);
>
> dbms_output.put_line('UTL Decompressed by Java Length: '
> || dbms_lob.getlength(uncompressed1));
>
> dbms_lob.freetemporary(uncompressed2);
>
> EXCEPTION
> WHEN OTHERS THEN
> dbms_output.put_line('Error encountered decompressing UTL '
> || 'Compressed BLOB with Java Decompress ('
> || SQLCODE || '): ' || SQLERRM);
> END;
>
>
> BEGIN
> uncompressed2 := utl_compress.lz_uncompress(compressed1);
>
> dbms_output.put_line('Java Uncompressed by UTL Length: '
> || dbms_lob.getlength(uncompressed2));
>
> dbms_lob.freetemporary(uncompressed1);
>
> EXCEPTION
> WHEN OTHERS THEN
> dbms_output.put_line('Error encountered decompressing Java '
> || 'Compressed BLOB with UTL Uncompress ('
> || SQLCODE || '): ' || SQLERRM);
> END;
>
> dbms_lob.freetemporary(compressed1);
> dbms_lob.freetemporary(compressed2);
>
> dbms_lob.close(uncompressed);
> dbms_lob.freetemporary(uncompressed);
>
> END;
> /
>
>
>
> I got the following output:
> Uncompressed Length: 3803470
> Java Compressed Length: 1307235
> UTL Compressed Length: 2266379
> Java Decompressed Length: 3803470
> UTL Uncompressed Length: 3803470
> Error encountered decompressing UTL Compressed BLOB with Java Decompress
> (-29532): ORA-29532: Java call terminated by uncaught Java exception:
> java.util.zip.ZipException: unknown compression method
> Error encountered decompressing Java Compressed BLOB with UTL Uncompress
> (-29294): ORA-29294: A data error occurred during compression or
> uncompression.
>
> That's 2.9:1 for Java Deflate and 1.68:1 for UTL_COMPRESS using the
> default quality of 6.
>
> Setting the quality to 9 for UTL_COMPRESS the output was:
> UTL Compressed Length: 2265869
> for UTL_COMPRESS, that's still 1.68:1
Has anyone tried this?
Received on Fri Jul 14 2006 - 03:37:30 CDT
