The UTL_COMPRESS package provides an API to allow compression and decompression of binary data (RAW, BLOB and BFILE). It uses the Lempel-Ziv compression algorithm which is equivalent to functionality of the gzip utility. A simple example of it's usage would be:
SET SERVEROUTPUT ON DECLARE l_original_blob BLOB; l_compressed_blob BLOB; l_uncompressed_blob BLOB; BEGIN -- Initialize both BLOBs to something. l_original_blob := TO_BLOB(UTL_RAW.CAST_TO_RAW('1234567890123456789012345678901234567890')); l_compressed_blob := TO_BLOB('1'); l_uncompressed_blob := TO_BLOB('1'); -- Compress the data. UTL_COMPRESS.lz_compress (src => l_original_blob, dst => l_compressed_blob); -- Uncompress the data. UTL_COMPRESS.lz_uncompress (src => l_compressed_blob, dst => l_uncompressed_blob); -- Display lengths. DBMS_OUTPUT.put_line('Original Length : ' || LENGTH(l_original_blob)); DBMS_OUTPUT.put_line('Compressed Length : ' || LENGTH(l_compressed_blob)); DBMS_OUTPUT.put_line('Uncompressed Length: ' || LENGTH(l_uncompressed_blob)); -- Free temporary BLOBs. DBMS_LOB.FREETEMPORARY(l_original_blob); DBMS_LOB.FREETEMPORARY(l_compressed_blob); DBMS_LOB.FREETEMPORARY(l_uncompressed_blob); END; / |
Fonte: http://www.oracle-base.com/articles/10g/PlsqlEnhancements10g.php
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