| General Information |
| Purpose |
Internal support for the supported UTL_COMPRESS package |
| Source |
$ORACLE_HOME/rdbms/admin/prvtcmpl.plb |
| Dependencies |
| DBMS_LOB |
DBMS_COMPRESS |
UTL_SYS_CMP_LIB |
|
| Security Model |
No privileges granted |
| Demo Table and Data |
Use the TEST table COMPRESS_DEMO procedure from the UTL_COMPRESS page |
| |
| ISOPEN |
| Checks to see if the handle to a piecewise operation context is open or closed |
utl_sys_compress.isopen(handle IN BINARY_INTEGER) RETURN BOOLEAN; |
| See LZ_UNCOMPRESS_EXTRACT Demo Below |
| |
| LZ_COMPRESS |
With an uncompressed BLOB as an input output a
compressed BLOB
Overload 1 |
utl_sys_compress.lz_compress(src IN BLOB, quality IN BINARY_INTEGER)
RETURN BLOB |
CREATE TABLE test (
fname VARCHAR2(30),
iblob BLOB);
Note: The directory CTEMP's creation can be found on the library page for directories (link below).
CREATE OR REPLACE PROCEDURE compress_demo(v_fname VARCHAR2, vQual BINARY_INTEGER) IS
src_file BFILE;
dst_file BLOB;
lgh_file BINARY_INTEGER;
i NUMBER;
BEGIN
src_file := bfilename('CTEMP', v_fname);
i := dbms_utility.get_time;
-- insert a NULL record to lock
INSERT INTO test
(fname, iblob)
VALUES
('Uncompressed', EMPTY_BLOB())
RETURNING iblob INTO dst_file;
-- lock record
SELECT iblob
INTO dst_file
FROM test
WHERE fname = 'Uncompressed'
FOR UPDATE;
-- open the file
dbms_lob.fileopen(src_file, dbms_lob.file_readonly);
-- determine length
lgh_file := dbms_lob.getlength(src_file);
-- read the file
dbms_lob.loadfromfile(dst_file, src_file, lgh_file);
-- update the blob field
UPDATE test
SET iblob = dst_file
WHERE fname = 'Uncompressed';
-- close file
dbms_lob.fileclose(src_file);
dbms_output.put_line(dbms_utility.get_time - i);
--=====================================================
i := dbms_utility.get_time;
-- insert a NULL record to lock
INSERT INTO test
(fname, iblob)
VALUES
('Compressed', EMPTY_BLOB())
RETURNING iblob INTO dst_file;
-- lock record
SELECT iblob
INTO dst_file
FROM test
WHERE fname = 'Compressed'
FOR UPDATE;
-- open the file
dbms_lob.fileopen(src_file, dbms_lob.file_readonly);
-- determine length
lgh_file := dbms_lob.getlength(src_file);
-- read the file
dbms_lob.loadfromfile(dst_file, src_file, lgh_file);
-- update the blob field
UPDATE test
SET iblob = utl_sys_compress.lz_compress(dst_file, vQual)
WHERE fname = 'Compressed';
COMMIT;
-- close file
dbms_lob.fileclose(src_file);
dbms_output.put_line(dbms_utility.get_time - i);
END compress_demo;
/
set serveroutput on
exec compress_demo('image1.dcm', 3);
SELECT fname, dbms_lob.getlength(iblob)
FROM test; |
With a BFILE as an input output a compressed
BLOB
Overload 2 |
utl_sys_compress.lz_compress(src IN BFILE, quality IN BINARY_INTEGER)
RETURN BLOB |
| TBD |
| |
| LZ_COMPRESS_ADD |
Adds a piece of
compressed data |
utl_sys_compress.lz_compress_add(
handle IN BINARY_INTEGER,
dst IN OUT BLOB,
src IN RAW) |
| TBD |
| |
| LZ_COMPRESS_BFILE |
With a BFILE as an input output a compressed BLOB |
utl_sys_compress.lz_compress_bfile(
src IN BFILE,
dst IN OUT BLOB,
quality IN BINARY_INTEGER); |
| TBD |
| |
| LZ_COMPRESS_BLOB |
With an uncompressed BLOB as an input output a compressed BLOB |
utl_sys_compress.lz_compress_blob(
src IN BLOB,
dst IN OUT BLOB,
quality IN BINARY_INTEGER); |
| TBD |
| |
| LZ_COMPRESS_CLOSE |
Closes and finishes a piecewise compress operation |
utl_sys_compress.lz_compress_close(
handle IN BINARY_INTEGER,
dst IN OUT BLOB); |
| TBD |
| |
| LZ_COMPRESS_OPEN |
Initializes a piecewise context that maintains the compress state and data |
utl_sys_compress.lz_compress_open(
dst IN OUT BLOB,
quality IN BINARY_INTEGER)
RETURN BINARY_INTEGER; |
| TBD |
| |
| LZ_UNCOMPRESS |
Uncompress BLOB to BLOB
Overload 1 |
utl_sys_compress.lz_uncompress(src IN BLOB) RETURN BLOB; |
set serveroutput
on
DECLARE
i NUMBER;
b BLOB;
BEGIN
i := dbms_utility.get_time;
SELECT iblob
INTO b
FROM test
WHERE fname = 'Uncompressed';
dbms_output.put_line('Uncompressed: ' ||
TO_CHAR(dbms_utility.get_time - i));
i := dbms_utility.get_time;
SELECT utl_sys_compress.lz_uncompress(iblob)
INTO b
FROM test
WHERE fname = 'Compressed';
dbms_output.put_line('Uncompress: ' ||
TO_CHAR(dbms_utility.get_time - i));
END;
/ |
Uncompress BFILE to BLOB
Overload 2 |
utl_sys_compress.lz_uncompress(src IN BFILE) RETURN BLOB; |
| TBD |
| |
| LZ_UNCOMPRESS_ BFILE |
Uncompress BFILE to BLOB |
utl_sys_compress.lz_uncompress_bfile(src IN BFILE, dst IN OUT BLOB); |
| TBD |
| |
| LZ_UNCOMPRESS_BLOB |
Uncompress BLOB to BLOB |
utl_sys_compress.lz_uncompress_blob(src IN BLOB, dst IN OUT BLOB); |
| TBD |
| |
| LZ_UNCOMPRESS_CLOSE |
| Closes and finishes a piecewise uncompress |
utl_sys_compress.lz_uncompress_close(handle IN BINARY_INTEGER); |
| See LZ_UNCOMPRESS_EXTRACT Demo Below |
| |
| LZ_UNCOMPRESS_EXTRACT |
Used by UTL_COMPRESS to extract a piece of uncompressed data which requires conversion to RAW.
Produces an ORA-29294 if used on an uncompressed BLOB |
utl_sys_compress.lz_uncompress_extract(
dst IN OUT RAW,
handle IN BINARY_INTEGER); |
set serveroutput on
DECLARE
bob BLOB;
rob RAW(32767);
handle BINARY_INTEGER;
amount INTEGER := 32766/2;
offset INTEGER := 1;
BEGIN
SELECT iblob
INTO bob
FROM test
WHERE fname = 'Compressed';
SELECT utl_sys_compress.lz_uncompress_open(bob)
INTO handle
FROM dual;
IF utl_sys_compress.isopen(handle) THEN
dbms_output.put_line(handle);
rob := dbms_lob.substr(bob, amount, offset);
dbms_output.put_line('Unextracted: ' || length(rob));
utl_sys_compress.lz_uncompress_extract(rob, handle);
dbms_output.put_line('Extracted: ' || length(rob));
utl_sys_compress.lz_uncompress_close(handle);
END IF;
END;
/ |
| |
| LZ_UNCOMPRESS_OPEN |
|
Initializes a piecewise context that maintain the uncompress state and data |
utl_sys_compress.lz_uncompress_open(src IN BLOB) RETURN BINARY_INTEGER; |
| See LZ_UNCOMPRESS_EXTRACT Demo Above |
