DBMS_SQL.COLUMN_VALUE throwing - > PL/SQL: numeric or value error: character string buffer too small error - plsql

Question

I am trying to dynamically execute a SQL in anonymous block and fetch the records using ':::' delimiter for external program.
It is failing when more than 13-15 records are fetched.
declare
mysql varchar2(3000) := 'select sid,username,status,event,p1,p2,p3 from v$session where rownum<30';
col DBMS_SQL.DESC_TAB;
data varchar2(4000);
state boolean;
function sqlformat ( col in DBMS_SQL.DESC_TAB, col_cnt number, indx number) return varchar2 AS
begin
if indx = col_cnt then
data := col(indx).col_name;
else
data := col(indx).col_name||':::';
end if;
return data;
end sqlformat;
function sqlexecute ( mysql IN varchar2) return boolean AS
handle number;
col_cnt number;
col DBMS_SQL.DESC_TAB;
v_exec number;
output varchar2(4000);
begin
handle := DBMS_SQL.OPEN_CURSOR;
DBMS_SQL.PARSE(handle, mysql, DBMS_SQL.NATIVE);
v_exec := DBMS_SQL.EXECUTE(handle);
DBMS_SQL.DESCRIBE_COLUMNS(handle, col_cnt, col);
FOR indx in 1..col_cnt
loop
data := sqlformat(col,col_cnt,indx);
DBMS_SQL.define_column(handle, indx, col(indx).col_name,4000);
output := output||data;
end loop;
dbms_output.put_line(output);
dbms_output.NEW_LINE();
while DBMS_SQL.fetch_rows(handle) > 0
loop
state:=True;
output := NULL;
data :=NULL;
FOR indx in 1..col_cnt
loop
DBMS_SQL.COLUMN_VALUE(handle, indx, col(indx).col_name);
data := sqlformat(col,col_cnt,indx);
output := output||data;
dbms_output.NEW_LINE();
end loop;
dbms_output.put_line(output);
end loop;
return state;
end;
begin
state :=sqlexecute(mysql);
end;
/
`SID:::USERNAME:::STATUS:::EVENT:::P1:::P2:::P3`
`1::::::ACTIVE:::rdbms ipc message:::100:::0:::0`
`3::::::ACTIVE:::rdbms ipc message:::300:::0:::0`
`4::::::ACTIVE:::rdbms ipc message:::300:::0:::0`
`5::::::ACTIVE:::DIAG idle wait:::3:::1:::0`
`6::::::ACTIVE:::watchdog main loop:::0:::20:::0`
`7::::::ACTIVE:::rdbms ipc message:::180000:::0:::0`
`8::::::ACTIVE:::rdbms ipc message:::100:::0:::0`
`9::::::ACTIVE:::rdbms ipc message:::300:::0:::0`
`10::::::ACTIVE:::ASM background timer:::0:::0:::0`
`11::::::ACTIVE:::Space Manager: slave idle wait:::1:::0:::0`
`13::::::ACTIVE:::class slave wait:::0:::0:::0`
`15::::::ACTIVE:::rdbms ipc message:::30000:::0:::0`
`17::::::ACTIVE:::Space Manager: slave idle wait:::2:::0:::0`
declare
*
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
ORA-06512: at "SYS.DBMS_SQL", line 1795
ORA-06512: at line 41
ORA-06512: at line 51

Answer 1

I suggest to try insert substr in each string objects to understand which variabile get the error:
data := substr(col(indx).col_name,1,4000);
data := substr(col(indx).col_name||':::',1,4000);
output := substr(output||data,1,4000);
output := substr(output||data,1,4000);
Thank you