Searching LONG datatype in Oracle - oracle

Question

I am looking for a way to search columns with a LONG datatype.
I know those are deprecated (and I've always hated working with them...), but for some reason Oracle themselves continue to use them in their own tables and views...
Basically I want to build a query on SYS.USER_TAB_SUBPARTITIONS with the WHERE-clause filtering a specific HIGH_VALUE.
HIGH_VALUE is of the LONG datatype and the only way I know to filter those things, is by using the undocumented function dbms_metadata_util.long2varchar
When executing a query with this function however, the returned value is NULL.
select sys.dbms_metadata_util.long2varchar(2000,'SYS.USER_TAB_SUBPARTITIONS','HIGH_VALUE', rowid) from USER_TAB_SUBPARTITIONS;
This is most likely because USER_TAB_SUBPARTITIONS is not actually a table, but a view. And views don't have rowids...
However, it seems to be a strange kind of view, as its definition does not show any underlying base table. Instead it just creates a synonym on itself.
So, to my actual question(s): Is there any other way to query LONG? Does anybody know the "base table" of USER_TAB_SUBPARTITIONS?

Answer 1

Yes, data type LONG in Oracle System-Views is a pain. When I have to use such values I use this one:
DECLARE
high_value INTEGER;
BEGIN
FOR aPart IN (SELECT * FROM USER_TAB_SUBPARTITIONS) LOOP
EXECUTE IMMEDIATE 'BEGIN :ret := '||aPart.HIGH_VALUE||'; END;' USING OUT high_value;
SELECT ...
WHERE ... = high_value;
end loop;
END;
Note, in this example HIGH_VALUE is an integer value. However, it can be anything else (e.g. a TIMESTAMP), consider this in your procedure. For example like this:
FUNCTION IntervalType(tableName IN VARCHAR2) RETURN VARCHAR2 IS
EXPRESSION_IS_OF_WRONG_TYPE EXCEPTION;
PRAGMA EXCEPTION_INIT(EXPRESSION_IS_OF_WRONG_TYPE, -6550);
ds INTERVAL DAY TO SECOND;
ym INTERVAL YEAR TO MONTH;
str VARCHAR2(1000);
BEGIN
SELECT INTERVAL
INTO str
FROM USER_PART_TABLES
WHERE TABLE_NAME = tableName;
EXECUTE IMMEDIATE 'BEGIN :ret := '||str||'; END;' USING OUT ym;
RETURN 'YEAR TO MONTH Interval of '||ym;
EXCEPTION
WHEN EXPRESSION_IS_OF_WRONG_TYPE THEN
EXECUTE IMMEDIATE 'BEGIN :ret := '||str||'; END;' USING OUT ds;
RETURN 'DAY TO SECOND Interval of '||ds;
END IntervalType;

Answer 2

If you query ALL_VIEWS or DBA_VIEWS, you will find the definition of the view USER_TAB_SUBPARTITIONS
SELECT TEXT
FROM all_views
WHERE view_name = 'USER_TAB_SUBPARTITIONS';
You will see that the HIGH_VALUE comes from hiboundval column of sys.tabsubpart$.
There is one other way we use to extract the HIGH_VALUE . You may use SUBSTR() to extract the exact values from the extracted HIGH_VALUE.
DECLARE
v_high_value VARCHAR2(100);
BEGIN
SELECT EXTRACTVALUE (
DBMS_XMLGEN.GETXMLTYPE (
'SELECT high_value
FROM all_tab_partitions
WHERE partition_name='''
|| YOUR_PARTITION_NAME
|| '''
AND table_owner='''
|| YOUR_TABLE_OWNER
|| '''
AND table_name='''
|| YOUR_TABLE
|| ''''),
'ROWSET/ROW/HIGH_VALUE') INTO v_high_value
FROM DUAL;
END;
/
You may refer Ask TOM article here