Hello again,
I managed to find out what caused the problem with the data space consumption
described below. (the remaining locks seems to be something else...)
I wrote a simple test program. Here the main part of it:
Class.forName("com.sap.dbtech.jdbc.DriverSapDB");
for (int i=0; i<50; i++)
{
System.out.println("cycle " + (i + 1) + " ");
lo_Connection =
DriverManager.getConnection("jdbc:sapdb://localhost/mydb", "user", "pwd");
lo_Statement = lo_Connection.prepareStatement("select * from mytable");
lo_ResultSet = lo_Statement.executeQuery();
while (lo_ResultSet.next())
{
}
lo_ResultSet.close();
lo_Statement.close();
lo_Connection.close();
Thread.sleep(50);
}
When I run this program every loop increases the amount of temporary data space needed
by my database by 8 KB. So after finishing the program the used temporary data space
was increased by 400 KB.
Somehow I found out that this can be avoided when I do not close the statement.
So changing the last block
lo_ResultSet.close();
lo_Statement.close();
lo_Connection.close();
to:
lo_ResultSet.close();
//lo_Statement.close();
lo_Connection.close();
fixes the problem.
This seems to be a problem in the JDBC driver.
I'd be very happy if someone who had similar problems or knows about this one could
drop me a line.
Right now the JDBC driver is a vital part of the project I'm currently working on. So
a fix or another version of the driver is very important.
Since I already know, where the problem occurs I'd be willing to fix it myself but in
that case I think I need some help from a developer of SAPDB.
I'd be very glad if someone answers...
with kind regards,
Steven Dolg
-----Urspr�ngliche Nachricht-----
Von: Steven Dolg
Gesendet: Mittwoch, 15. Januar 2003 17:09
An: '[EMAIL PROTECTED]'
Betreff: persitent locks and data space consumption
Hello,
I'm having difficulties using SAPDB 7.3.0.29 on Win2000.
Using a Java application (with the latest JDBC driver) I write into the
database updating a row (I receive signs of life from another machine and store the
time of arrival in the database)
Using the Database Manager 7.4.2.6 I watched the number of locks on the
database (instance -> information -> locks).
The thing that confuses me is that the number of locks (both row and table
locks) only increases. It really never decreases even if I shut down my application.
Referring to the manual this is the number of currently held locks. It is
possible that there are more than 10.000 table locks in a database containing about 30
tables? (The request timeout is 30 seconds).
There is another problem which I think is related to this: (still the same
application mentioned above)
In some special occasions the remote machine does not send a sign of life but
an alert. In this case there a some actions needed to be taken.
This causes the application to perform a number of additional database
operations (like storing the alert message...)
For tests I created an alert every 2 seconds (which resulted in an increased
but not extrem load).
After about 100 alerts the available space for data started to shrink extrem
fast. Of course rows were inserted but the space was consumed much faster than
anticipated. Finally the data space usage reached 50 % (starting at 13 % of 100 MB).
At this point no more operations on the database were possible.
After restarting the database (online -> offline -> online) the data space
usage was back about the value before my test (there was a negligible increase due to
the added data).
The same application already completed test runs with more than 15.000 alerts
when using MySql oder MS SQL-Server. A similar situation never occured there.
I'd be grateful for any help I could get (since I'm quite new to SAPDB).
i. A. Steven Dolg
Software Developer
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