CLOB to NCLOB conversion in Oracle 9i

Question

Hi,
I have a table with 8 million records. The table has a clob column that has to be converted in to a nclob column. I have writtten a procedure for the clob to nclob conversion using cursors and the limit functionality.The procedure is given as follows:
CREATE OR REPLACE PROCEDURE pr_clob_to_nclob is
TYPE type_dockey IS TABLE OF inf_doc_store.ds_doc_key%TYPE INDEX BY PLS_INTEGER;
l_type_dockey type_dockey;
TYPE type_rowid IS TABLE OF VARCHAR(100) INDEX BY PLS_INTEGER;
l_type_rowid type_rowid;
L_NUMERRORS NUMBER := 0;
E_BULKINS_ILCHIS_EXCEPTION EXCEPTION;
E_BULKINS_ELCHIS_EXCEPTION EXCEPTION;
E_BULKINS_ILCTXN_EXCEPTION EXCEPTION;
E_BULKINS_ELCTXN_EXCEPTION EXCEPTION;
L_ERR_MESSAGE INF_ERROR_LOG.ERROR_TEXT%TYPE;
L_FILE UTL_FILE.FILE_TYPE;
CURSOR l_doc_store IS SELECT ds_doc_key,rowid from inf_doc_store where ds_doc_content1 is null;
BEGIN
--OPEN l_doc_store FOR 'select ds_doc_key,rowid from inf_doc_store1';
OPEN l_doc_store;
LOOP
FETCH l_doc_store BULK COLLECT INTO l_type_dockey,l_type_rowid LIMIT 5000;
BEGIN
FORALL docidx IN 1 .. l_type_dockey.COUNT SAVE EXCEPTIONS
UPDATE inf_doc_store SET DS_DOC_CONTENT1 = TO_NCLOB(DS_DOC_CONTENT)
WHERE ROWID =l_type_rowid(docidx);
EXCEPTION
WHEN OTHERS THEN
L_NUMERRORS := SQL%BULK_EXCEPTIONS.COUNT;
FOR IDX IN 1 .. L_NUMERRORS LOOP
L_ERR_MESSAGE := 'on bulk insert : Error in Doc key << ' ||
l_type_dockey(IDX) || ' >> index << ' ||
SQL%BULK_EXCEPTIONS(IDX)
.ERROR_INDEX || ' IS ' ||
SQLERRM(0 - SQL%BULK_EXCEPTIONS(IDX)
.ERROR_CODE) || ' >>';
PKG_INF_COMMON.PR_LOG_ERROR('CLOB_TO_NCLOB Migration',
'inf_doc_store',
L_ERR_MESSAGE,
'NA');
PKG_INF_COMMON.PR_UTL_PUTLINE(L_FILE,
L_ERR_MESSAGE,
'NA');
END LOOP;
PKG_INF_COMMON.PR_UTL_FCLOSE(L_FILE, 'inf_doc_store_updation');
RAISE E_BULKINS_ILCHIS_EXCEPTION;
END;
COMMIT;
EXIT WHEN l_doc_store%NOTFOUND;
END LOOP;
CLOSE l_doc_store;
END pr_clob_to_nclob;
The table in which the clob column is to be converted is inf_doc_header.
The above procedure runs successfully but takes more than 48 hours to convert all the records.
Can any body suggest me a way to optimise the procedure?
Regards,
Siddarth

Answer 1

Hi,
I have a table with 8 million records. The table has a clob column that has to be converted in to a nclob column. I have writtten a procedure for the clob to nclob conversion using cursors and the limit functionality.The procedure is given as follows:
CREATE OR REPLACE PROCEDURE pr_clob_to_nclob is
TYPE type_dockey IS TABLE OF inf_doc_store.ds_doc_key%TYPE INDEX BY PLS_INTEGER;
l_type_dockey type_dockey;
TYPE type_rowid IS TABLE OF VARCHAR(100) INDEX BY PLS_INTEGER;
l_type_rowid type_rowid;
L_NUMERRORS NUMBER := 0;
E_BULKINS_ILCHIS_EXCEPTION EXCEPTION;
E_BULKINS_ELCHIS_EXCEPTION EXCEPTION;
E_BULKINS_ILCTXN_EXCEPTION EXCEPTION;
E_BULKINS_ELCTXN_EXCEPTION EXCEPTION;
L_ERR_MESSAGE INF_ERROR_LOG.ERROR_TEXT%TYPE;
L_FILE UTL_FILE.FILE_TYPE;
CURSOR l_doc_store IS SELECT ds_doc_key,rowid from inf_doc_store where ds_doc_content1 is null;
BEGIN
--OPEN l_doc_store FOR 'select ds_doc_key,rowid from inf_doc_store1';
OPEN l_doc_store;
LOOP
FETCH l_doc_store BULK COLLECT INTO l_type_dockey,l_type_rowid LIMIT 5000;
BEGIN
FORALL docidx IN 1 .. l_type_dockey.COUNT SAVE EXCEPTIONS
UPDATE inf_doc_store SET DS_DOC_CONTENT1 = TO_NCLOB(DS_DOC_CONTENT)
WHERE ROWID =l_type_rowid(docidx);
EXCEPTION
WHEN OTHERS THEN
L_NUMERRORS := SQL%BULK_EXCEPTIONS.COUNT;
FOR IDX IN 1 .. L_NUMERRORS LOOP
L_ERR_MESSAGE := 'on bulk insert : Error in Doc key << ' ||
l_type_dockey(IDX) || ' >> index << ' ||
SQL%BULK_EXCEPTIONS(IDX)
.ERROR_INDEX || ' IS ' ||
SQLERRM(0 - SQL%BULK_EXCEPTIONS(IDX)
.ERROR_CODE) || ' >>';
PKG_INF_COMMON.PR_LOG_ERROR('CLOB_TO_NCLOB Migration',
'inf_doc_store',
L_ERR_MESSAGE,
'NA');
PKG_INF_COMMON.PR_UTL_PUTLINE(L_FILE,
L_ERR_MESSAGE,
'NA');
END LOOP;
PKG_INF_COMMON.PR_UTL_FCLOSE(L_FILE, 'inf_doc_store_updation');
RAISE E_BULKINS_ILCHIS_EXCEPTION;
END;
COMMIT;
EXIT WHEN l_doc_store%NOTFOUND;
END LOOP;
CLOSE l_doc_store;
END pr_clob_to_nclob;
The table in which the clob column is to be converted is inf_doc_header.
The above procedure runs successfully but takes more than 48 hours to convert all the records.
Can any body suggest me a way to optimise the procedure?
Regards,
Siddarth