Reading clob line by line with pl\sql

Question

In my project i use oracle as primary database and i\'ve faced a problem with parsing clob. So suppose we have a clob with value

   aaaaaa
   cccccc
   bbbbb         


        

Answer 1

A pipelined function with some additional options to drive the behavior. Tested/works on Windows, Oracle 11g (I have some suspicions it may fail in *nix environments because of how lines terminate).

CREATE OR REPLACE FUNCTION ETL_HELPER_PARSE
   (P_CLOB NCLOB, P_LINES_TO_SKIP INT DEFAULT 0, P_PUT_EMPTY_LINES CHAR DEFAULT 'N') RETURN SYS.ODCIVarchar2List PIPELINED
AS
  c_top_lines_to_skip  CONSTANT NUMBER  NOT NULL := P_LINES_TO_SKIP;
  c_output_empty_lines CONSTANT CHAR(1) NOT NULL := P_PUT_EMPTY_LINES; 
  --
  l_len     INT := DBMS_LOB.GETLENGTH(P_CLOB);
  l_hit     INT := 0;
  l_offset  INT := 1;
  l_amount  INT;  
  l_buffer  VARCHAR2(32767);
  l_cnt     INT := 1;  
BEGIN  
  WHILE ( l_offset < l_len )
  LOOP
    l_hit := DBMS_LOB.INSTR (
     lob_loc    => P_CLOB           -- IN   CLOB      CHARACTER SET ANY_CS
    ,pattern    => CHR(13)||CHR(10) -- IN   VARCHAR2  CHARACTER SET lob_loc%CHARSET
    ,offset     => l_offset         -- IN   INTEGER := 1
    ,nth        => 1                -- IN   INTEGER := 1
    );
    l_amount := CASE WHEN COALESCE(l_hit, 0) > 0 THEN l_hit - l_offset ELSE l_len - l_offset + 1 END;
    -- `l_amount=0` means a new empty line has been encountered
    IF l_cnt > c_top_lines_to_skip       
    THEN
      IF l_amount > 0
      THEN
        DBMS_LOB.READ(P_CLOB, l_amount, l_offset, l_buffer);
        PIPE ROW (l_buffer);
      ELSIF UPPER(c_output_empty_lines) = 'Y'
      THEN
        PIPE ROW ('');
      END IF;
    END IF;

    l_offset := CASE WHEN COALESCE(l_hit, 0) > 0  THEN l_hit + 2 ELSE l_len END;    
    l_cnt := l_cnt + 1;
  end loop;
EXCEPTION
  WHEN OTHERS THEN
     DBMS_OUTPUT.PUT_LINE('Error : '||SQLERRM);
END ETL_HELPER_PARSE;