How to find Ref Cursor execution time in procedure? - oracle

Question

I'm using Ref Cursor as output parameter for PLSQL Procedure. I need to maintain the exact start and end time of proc in log table.
The dummy code below:
Procedure(P1 IN NUMBER, P_REF_CUR OUT SYS_REFCURSOR)
IS
V_TS TIMESTAMP;
BEGIN
V_TS := SYSTIMESTAMP;
<Business logic here to generate SELECT query for Ref Cursor...>;
OPEN P_REF_CUR FOR <SELECT QUERY>;
INSERT INTO LOG_TABLE(ID, STR_TIME,END_TIME,..) VALUES
(1,V_TS,SYSTIMESTAMP,...);
END;
The select query for Ref Cursor sometimes takes 2-3 mins to execute but in log table I see the difference between STR_TIME and END_TIME as only few seconds.
How can I capture the total time taken by procedure including the query execution time?

Answer 1

Once your procedure hands the ref cursor back to the calling process, it has no way of knowing what will happen to it. The caller may never even fetch all of the rows from the cursor. It’s for the caller to log what happens next.

Answer 2

You may try to split this procedure into two packaged procedures, and apply set timing on :
SQL> create or replace package myPkg is
procedure pr1(P1 IN NUMBER);
procedure pr2(P_REF_CUR OUT SYS_REFCURSOR);
end;
/
SQL> create or replace package body myPkg is
v_ts timestamp;
procedure pr1(P1 IN NUMBER) is
begin
v_ts := SYSTIMESTAMP;
<Business logic here to generate SELECT query for Ref Cursor...>;
end;
procedure pr2(P_REF_CUR OUT SYS_REFCURSOR) is
begin
open P_REF_CUR for <SELECT QUERY>;
insert into log_table(ID, STR_TIME,END_TIME,..) values(1,V_TS,SYSTIMESTAMP,...);
end;
end;
/
SQL> set timing on;
SQL> var v_p1 number:=107;
SQL> var v_rc refcursor;
SQL> exec myPkg.pr1( :v_p1 );
PL/SQL procedure successfully completed
Executed in 152,25 seconds
SQL> exec myPkg.pr2( :v_rc );
PL/SQL procedure successfully completed
Executed in 12,34 seconds
SQL> print v_rc;

Answer 3

You can't tell from inside the procedure. The OPEN FOR statement:
... associates a cursor variable with a query, allocates database resources to process the query, identifies the result set, and positions the cursor before the first row of the result set.
All you can time in your procedure is how long it takes to generate the query text and how long it takes to open the cursor. The procedure then ends, and the caller takes over the OUT ref cursor. You can't see anything about what happens to the cursor from here.
The caller than (presumably) fetches the data, which is taking the bulk of the time; but may also be doing other processing. You need the caller to log the time between it calling your procedure and when it closes the ref cursor when it's finished with it - but that will still include any additional processing it does, so you can't separate out how much is actually from the cursor query processing and fetching.
If that is close enough then you could potentially have a second procedure that closes the cursor and logs the time, if you don't want that the caller to have to worry about it. You could have the 'open' cursor record the start time in a session variable (making the package stateful) and have the 'close' procedure retrieve that and insert the logging record; or have the 'open' do the initial insert into the logging table with a null end time, and then have the 'close' update that record with the actual end time. But again, it's only approximate.
if you really want to do it all in that procedure then you would have to do all the query processing within it, which probably means bulk collecting the cursor into a collection and using that collection type as the OUT parameter, adjusting your caller to iterate over that instead of the cursor. That has more memory overhead too of course, so may not be practical.