| General Information |
Note: Performs Lempel-Ziv compression of RAW and BLOB data
It is the caller's responsibility to free the temporary LOB returned
by the LZ* functions with DBMS_LOB.FREETEMPORARY call. |
| Source |
{ORACLE_HOME}/rdbms/admin/utlcomp.sql |
| Constants |
|
Constant |
Purpose |
Value |
|
UTLCOMP_MAX_HANDLE
|
Define the maximum number of handles for piecewise operations
|
5
|
|
| Dependencies |
| UTL_CMP_LIB |
UTL_SYS_COMPRESS |
|
Exceptions |
| Exception Name |
Error Code |
Reason |
| INVALID_ARGUMENT |
29261 |
Argument(s) of an invalid type or value |
| STREAM_ERROR |
29293 |
Error during compression or uncompression |
| DATA_ERROR |
29294 |
Invalidly formatted input or output stream |
| BUFFER_TOO_SMALL |
29297 |
Compressed representation is too large |
| INVALID_HANDLE |
29299 |
Invalid handle for piecewise (un)compress |
|
| |
| ISOPEN |
|
Checks to see if the handle to a piecewise operation context is open or closed |
utl_compress.isopen(handle IN BINARY_INTEGER) RETURN BOOLEAN; |
| See LZ_COMPRESS_ADD Demo Below |
| |
| LZ_COMPRESS |
Compress BLOB
Overload 1
|
utl_compress.lz_compress(
src IN BLOB,
quality IN BINARY_INTEGER DEFAULT 6)
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_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
SELECT fname, dbms_lob.getlength(iblob)
FROM test; |
| Compress RAW
Overload 2
|
utl_compress.lz_compress(
src IN RAW,
quality IN BINARY_INTEGER DEFAULT 6)
RETURN RAW; |
| TBD |
| Compress BFILE
Overload 3
|
utl_compress.lz_compress(
src IN BFILE,
quality IN BINARY_INTEGER DEFAULT 6)
RETURN BLOB; |
| TBD |
| Compress BLOB
Overload 4
|
utl_compress.lz_compress(
src IN BLOB,
dst IN OUT NOCOPY BLOB
quality IN BINARY_INTEGER DEFAULT 6) RETURN BLOB; |
| TBD |
| Compress BLOB
Overload 5
|
utl_compress.lz_compress(
src IN BFILE,
dst IN OUT NOCOPY BLOB
quality IN BINARY_INTEGER DEFAULT 6) RETURN BLOB; |
| TBD |
| |
| LZ_COMPRESS_ADD |
Adds a piece of
compressed data |
utl_compress.lz_compress_add(
handle IN BINARY_INTEGER,
dst IN OUT NOCOPY BLOB,
source IN RAW); |
DECLARE
b BLOB;
r RAW(32);
handle BINARY_INTEGER;
BEGIN
SELECT iblob
INTO b
FROM test
WHERE fname = 'Uncompressed'
FOR UPDATE;
handle := utl_compress.lz_compress_open(b);
IF NOT utl_compress.isopen(handle) THEN
RAISE NO_DATA_FOUND;
END IF;
r := utl_raw.cast_to_raw('ABC');
utl_compress.lz_compress_add(handle, b, r);
utl_compress.lz_compress_close(handle, b);
END;
/ |
| |
| LZ_COMPRESS_CLOSE |
| Closes and finishes a piecewise compress operation |
utl_compress.close(
handle IN BINARY_INTEGER,
dst IN OUT NOCOPY BLOB); |
| See LZ_COMPRESS_ADD Demo Below |
| |
| LZ_COMPRESS_OPEN |
Initializes a piecewise context that maintains the compress state and data |
utl_compress.lz_compress_open(
data_source IN BLOB,
quality IN BINARY_INTEGER DEFAULT 6);
quality can be from 1 to 9 with 1 being fastest and 9 the slowest |
| See LZ_COMPRESS_ADD Demo Below |
| |
| LZ_UNCOMPRESS |
Uncompress BLOB to BLOB
Overload 1 |
utl_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_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 RAW to RAW
Overload 2 |
utl_compress.lz_uncompress(src IN RAW) RETURN RAW; |
| TBD |
Uncompress BFILE to BLOB
Overload 3 |
utl_compress.lz_uncompress(src IN BFILE) RETURN BLOB
|
| TBD |
Uncompress BLOB to BLOB
Overload 4 |
utl_compress.lz_uncompress(src IN BLOB, dst IN OUT NOCOPY BLOB);
|
| TBD |
Uncompress BFILE into BLOB
Overload 5 |
utl_compress.lz_uncompress(src IN BFILE, dst IN OUT NOCOPY BLOB)
|
| TBD |
| |
| LZ_UNCOMPRESS_CLOSE |
| Closes and finishes a piecewise uncompress |
utl_compress.lz_uncompress_close(handle IN BINARY_INTEGER) |
| See LZ_UNCOMPRESS_EXTRACT Demo Below |
| |
| LZ_UNCOMPRESS_EXTRACT |
Extracts a piece of uncompressed data |
utl_compress.lz_compress_uncompress_extract(
handle IN BINARY_INTEGER,
dst OUT NOCOPY RAW); |
DECLARE
ib BLOB;
ob BLOB;
dst_file BLOB;
handle BINARY_INTEGER;
BEGIN
SELECT iblob
INTO ib
FROM test
WHERE fname = 'Compressed';
SELECT utl_compress.lz_uncompress_open(ib)
INTO handle
FROM dual;
utl_compress.lz_uncompress_extract(handle,
ob);
INSERT INTO test
(fname, iblob)
VALUES
('Extracted', EMPTY_BLOB())
RETURNING iblob INTO dst_file;
-- lock record
SELECT iblob
INTO dst_file
FROM test
WHERE fname = 'Extracted'
FOR UPDATE;
UPDATE test
SET iblob = ob
WHERE fname = 'Extracted';
COMMIT;
utl_compress.lz_uncompress_close(handle);
COMMIT;
END;
/
SELECT fname, dbms_lob.getlength(iblob)
FROM test; |
| |
|
LZ_UNCOMPRESS_OPEN
|
|
Initializes a piecewise context that maintain the uncompress state and data |
utl_compress.lz_uncompress_open(src IN BLOB) RETURN BINARY_INTEGER
|
| See LZ_UNCOMPRESS_EXTRACT Demo Above |
