Thread: Re: pgsql-sq-owner
Hi,
I am using below code in multi threaded environment, but when multiple threads are accessing then i get : "org.postgresql.util.PSQLException: ERROR: tuple concurrently updated" exception. But my concern is I need to use it in multi threaded env, for the same reason I am using FOR UPDATE with cursor. Then where is the issue??? Am I missing something????? Please help me with the same.....
Statement stmt = c.createStatement();// Setup function to call.
stmt.execute("CREATE OR REPLACE FUNCTION refcursorfunc() RETURNS refcursor AS '"
+ " DECLARE "
+ " call_log_rec call_log % rowtype; "
+ " call_log_cursor refcursor; "
+ " final_cursor refcursor; "
+ " idInt int[]; "
+ " BEGIN "
+ " OPEN call_log_cursor FOR SELECT * FROM call_log WHERE aht_read_status = 0 ORDER BY record_sequence_number ASC limit 20 FOR UPDATE; "
+ " LOOP "
+ " FETCH NEXT FROM call_log_cursor INTO call_log_rec; "
+ " EXIT WHEN call_log_rec IS NULL; "
+ " UPDATE call_log SET aht_read_status = 1 WHERE CURRENT OF call_log_cursor; "
+ " idInt := idInt || ARRAY [call_log_rec.record_sequence_number]; "
+ " END LOOP;"
+ " OPEN final_cursor FOR SELECT record_sequence_number FROM call_log WHERE record_sequence_number = ANY(idInt); "
+ " RETURN final_cursor; "
+ " END;' language plpgsql");
stmt.close();
// We must be inside a transaction for cursors to work.
c.setAutoCommit(false);
// Procedure call.
CallableStatement proc = c.prepareCall("{ ? = call refcursorfunc() }");
proc.registerOutParameter(1, Types.OTHER);
System.out.println("BEFORE::: Thread name::: " + Thread.currentThread().getName());
proc.execute();
ResultSet results = (ResultSet) proc.getObject(1);
while (results.next()) {
// do something with the results...
System.out.println("Hurrey got the results from SP........");
System.out.println("AFTER::::Thread name::: " + Thread.currentThread().getName()+ " record_sequence_number:::: "+results.getString(1));
}
c.commit();
results.close();
proc.close();
Thanks in advance Alma
On Thursday, 27 February 2014 5:38 PM, ALMA TAHIR <almaheena2003@yahoo.co.in> wrote:
Hi,
It would be very helpful if anyone could help me with below issue.
I am using below stored proc:
CREATE OR REPLACE FUNCTION FETCH_CALL_LOGS() RETURNS refcursor AS $$
DECLARE
call_log_rec call_log % rowtype;
call_log_cursor refcursor;
BEGIN
OPEN call_log_cursor FOR
SELECT *
FROM
call_log
WHERE aht_read_status = 0
ORDER BY record_sequence_number ASC limit 20 FOR UPDATE;
LOOP
FETCH NEXT FROM call_log_cursor INTO call_log_rec;
EXIT WHEN call_log_rec IS NULL;
UPDATE call_log SET aht_read_status = 1 WHERE record_sequence_number = call_log_rec.record_sequence_number;
END LOOP;
RETURN call_log_cursor;
END;
$$ LANGUAGE plpgsql;
DECLARE
call_log_rec call_log % rowtype;
call_log_cursor refcursor;
BEGIN
OPEN call_log_cursor FOR
SELECT *
FROM
call_log
WHERE aht_read_status = 0
ORDER BY record_sequence_number ASC limit 20 FOR UPDATE;
LOOP
FETCH NEXT FROM call_log_cursor INTO call_log_rec;
EXIT WHEN call_log_rec IS NULL;
UPDATE call_log SET aht_read_status = 1 WHERE record_sequence_number = call_log_rec.record_sequence_number;
END LOOP;
RETURN call_log_cursor;
END;
$$ LANGUAGE plpgsql;
and trying to read response in java:
java.sql.CallableStatement proc = c.prepareCall("{ ? = call fetch_call_logs() }");
c.setAutoCommit(false);
proc.registerOutParameter(1, java.sql.Types.OTHER);
proc.execute();
ResultSet rset2 = (ResultSet) proc
.getObject(1);
while (rset2.next()) {
System.out.println(rset2
.getString(1));
}
rset2.close();
// c.setAutoCommit(false);
proc.close();
c.close();
c.setAutoCommit(false);
proc.registerOutParameter(1, java.sql.Types.OTHER);
proc.execute();
ResultSet rset2 = (ResultSet) proc
.getObject(1);
while (rset2.next()) {
System.out.println(rset2
.getString(1));
}
rset2.close();
// c.setAutoCommit(false);
proc.close();
c.close();
but i ma not able to get proper response back... if i comment out the fetch statement and tried doing some static update i am able to get proper response back. Stucked up with this...
I want to open a ref cursor with select for update and then update the records and get the ref cursor in response back in java.
But its not happening .... if i return ref cursor only after select it works fine but after fetch when i am returning the response back i am not getting..
Where am I doing the mistake or anything I am missing???? Please help me with the same ... it would be very helpful.....But its not happening .... if i return ref cursor only after select it works fine but after fetch when i am returning the response back i am not getting..
On 03/03/2014 09:35 PM, ALMA TAHIR wrote: > Hi, > > I am using below code in multi threaded environment, but when multiple > threads are accessing then i get : "org.postgresql.util.PSQLException: > ERROR: tuple concurrently updated" exception. But my concern is I need > to use it in multi threaded env, for the same reason I am using FOR > UPDATE with cursor. Then where is the issue??? Am I missing > something????? Please help me with the same.... So I assume this is a second attempt at your previous thread ' Function Issue'. I will respond on the previous thread to keep it intact. > > -- Adrian Klaver adrian.klaver@aklaver.com