Read CLOB column - piece-wise break-up

Question

I have two tables File_Master and File_Detail
File_Master Primary key FILE_ID
File_Detail Primary key FILE_ID,LINE_ID
I have a CLOB column FILE_CONTENT in table File_Master.
For every FILE_ID record in File_Master, several hundreds of lines are stored in the CLOB column.
I want to read this CLOB column 'File_Content' and and break every line (1000 Characters)
piecewise to populate columns of File_Detail.
Since there will be thousands of lines to process, what would be the best approach in writing PL/SQL code for better performance?
Thanks in advance.

Answer 1

Do you want actual lines (terminated by a Unix or DOS linefeed) from the CLOB?
I use the following function for processing lines from CLOBs (and then further tokenising and parsing each line):
create or replace type TStrings is table of varchar2(4000);
create or replace function ClobToLines( c clob, lineTerminator varchar2 default null  ) return TStrings pipelined is
-- function:    CLOB TO LINES
-- descr:       reads lines from a clob and returns each line as a separate row
        pos     integer;
        line    varchar2(4000);
        offset  integer := 1;
        charSep varchar2(10);
        amount  integer := 1;
begin
        -- if no CRLF specified, detect whether DOS or Unix linefeeds are used
        if lineTerminator is null then
                pos := DBMS_LOB.InStr( c, chr(10), offset, 1 );
                if pos = 0 then
                        raise_application_error(
                                -20001,
                                'The CLOB does not contain char #10 (used by both DOS and Unix linefeeds) and failed to parse.'
                end if;
                if pos > 1 then
                        DBMS_LOB.Read(
                                lob_loc => c,
                                amount => amount,
                                offset => pos-1,
                                buffer => charSep
                end if;
                if charSep = chr(13) then
                        charSep := chr(13)||chr(10);
                else
                        charSep := chr(10);
                end if;
        else
                charSep := lineTerminator;
        end if;
        while (offset < DBMS_LOB.GetLength(c) )  loop
                pos := DBMS_LOB.InStr( c, charSep, offset, 1 );
                if pos > 0 then
                        line := DBMS_LOB.SubStr( c, pos-offset, offset );
                        offset := pos + length(charSep);
                else
                        offset := DBMS_LOB.GetLength( c ) + 1;
                        line := null;
                end if;
                pipe row( line );
        end loop;
        return;
end;
/