using long string(over 4000) in oracle query

Question

I know that in sql varchar2 can only be around 4000.

I know that in oracle PL varchcar2 can be around 32000.

I have a varchar2 variable defined that is over 4000 characters long and I want to use it in a query. I don't want to insert the value into a table. The value is a dilimited string that I am parsing and inserting into a table with this query. This query works when the variable is less than 4000 characters long. Is there a way to make it work with up to 32000 characters?

create global temporary table t(single_element varchar(500),element_no number);
declare
--declared as 32767 but this string contains less than 4000 characters. 
--This will work. If you expand the string to 32000 characters it will not work.
myvar varchar2(32767) := 'tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4^~tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testmsg4';
begin
delete from t;
insert into t
SELECT SUBSTR(str, start_pos, (next_pos-start_pos)) AS single_element, element_no
FROM  (
        SELECT 
              ilv.str, 
              nt.column_value AS element_no, 
              INSTR(ilv.str, '^~', DECODE(nt.column_value, 1, 0, 1), DECODE(nt.column_value, 1, 1, nt.column_value-1)) + 2 AS start_pos,
              INSTR(ilv.str, '^~', 1, DECODE(nt.column_value, 1, 1, nt.column_value)) AS next_pos
        FROM   (
                select '~' || myvar || '^~' as str, 
                (Length(myvar) - length(replace(myvar,'^~','')))/2 + 2 as no_of_elements 
                from dual) ilv,

              TABLE(
                    CAST(
                       MULTISET(
                          SELECT ROWNUM FROM dual CONNECT BY ROWNUM < ilv.no_of_elements
                          ) AS number_ntt )) nt
         );
end;

The error I get when expanding "myvar" to 32000 characters is

can bind a LONG value only for insert into a LONG column

Is there a way I can get around this size restraint because i'm not actually inserting this value into a table, i'm just using it in the query?

Answer 1

Do you have to define the variable as a VARCHAR2? Could you define it as a CLOB instead?

If I change the declaration of MYVAR from a VARCHAR2(32767) to a CLOB and define the NUMBER_NTT type, your code runs for me

SQL> ed
Wrote file afiedt.buf

SP2-0161: line 2 truncated.
  1  declare
  2  myvar clob := 'tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3^~tcd4~#testms
  <<snip>>
~tcd3~#testmsg3^~tcd4~#testmsg4';
  4  begin
  5  delete from t;
  6  insert into t
  7  SELECT SUBSTR(str, start_pos, (next_pos-start_pos)) AS single_element, elem
ent_no
  8  FROM  (
  9          SELECT
 10                ilv.str,
 11                nt.column_value AS element_no,
 12                INSTR(ilv.str, '^~', DECODE(nt.column_value, 1, 0, 1), DECODE
(nt.column_value, 1, 1, nt.column_value-1)) + 2 AS start_pos,
 13                INSTR(ilv.str, '^~', 1, DECODE(nt.column_value, 1, 1, nt.colu
mn_value)) AS next_pos
 14          FROM   (
 15                  select '~' || myvar || '^~' as str,
 16                  (Length(myvar) - length(replace(myvar,'^~','')))/2 + 2 as n
o_of_elements
 17                  from dual) ilv,
 18                TABLE(
 19                      CAST(
 20                         MULTISET(
 21                            SELECT ROWNUM FROM dual CONNECT BY ROWNUM < ilv.n
o_of_elements
 22                            ) AS number_ntt )) nt
 23           );
 24* end;
 25  /

PL/SQL procedure successfully completed.

SQL> select count(*) from t;

  COUNT(*)
----------
       172

That being said, that's not how I'd parse a delimited string, particularly in PL/SQL. But it does the job.

Answer 2

OK, well this skirts close to the edges of your implementation bias, although remember that forall IS a bulk-binding operation, not a real loop, but have you looked at the dbms_utility.comma_to_table function?

It is an optimized internal oracle parsing function, although with some limitations as you can read about here: http://www.techiegyan.com/2009/02/17/oracle-breaking-comma-separated-string-using-dbms_utilitycomma_to_table/

You would need to replace() to make it comma-delimited, and also double-quotes-enclose if you have parsed fields that starts with numbers, special characters, contains commas, etc

But if your data will allow - it sure makes your code look cleaner (and will likely work much faster too)

declare
   myvar      varchar2(32000) := 'tcd1~#testmsg1^~tcd2~#testmsg2^~tcd3~#testmsg3';
   mycnt      binary_integer;
   myresults  sys.dbms_utility.lname_array;
begin
   sys.dbms_utility.comma_to_table('"'||replace(myvar,'^~','","')||'"', mycnt, myresults );
   delete from t;
   forall ix in myresults.first..myresults.last 
      insert into tvalues (myresults(ix));
   commit;
end;