Questions on Lob-Columns

Question

Hi,
i´m working still along time with Oracle, but not very often with Lob-Types.
The docs and metalink didn´t helped me very much with the following questions:
1. What is the maximum length of a CLOB Datatype in PL/SQL (long ago it was 32767 Bytes, but now (10.2) ?)
2. Is empty_blob()/empty_clob() still necessary in 10.2? or when do i use it?
3. What is the maximum length of a pl/sql clob datatype when i update a clob column in a table?
declare
c clob;
begin
c:=.......... very long;
update t set col=c where id=1;
end;
4. Does a select in pl/sql return a locator or the data ob the lob (If locator, is there a easy way the read the contents of a clob without dbms_lob.read?)
5. Is there dbms_lob Package faster/better/??? then using insert/update/delete direct on the column?
Thanks
Marco
Message was edited by:
mpatzwah

Answer 1

You may find the following link useful:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements001.htm#sthref173
E.g., search for CLOB yields:
CLOB objects can store up to (4 gigabytes -1) * (the value of the
CHUNK parameter of LOB storage) of character data.
If the tablespaces in your database are of standard block size,
and if you have used the default value of the CHUNK parameter
of LOB storage when creating a LOB column, then this is
equivalent to (4 gigabytes - 1) * (database block size).
CLOB objects have full transactional support. Changes made
through SQL, the DBMS_LOB package, or the Oracle Call
Interface (OCI) participate fully in the transaction.
CLOB value manipulations can be committed and rolled back.
However, you cannot save a CLOB locator in a PL/SQL or
OCI variable in one transaction and then use it in another
transaction or session.