Hi
I have an application that uses JMS to persist entities to a DB, I am
using Glassfish UR1 using table generator for the primary key generator,
using the default allocation size as 50. One problem that I had was
when an unexpected row in the DB appeared.
The table sequence count was say 50, meaning that the application held
51-100 in memory for primary keys, and a row appeared in at 101
unexpectedly. I am not sure how this came about, the application is the
only thing using this DB, but I have been testing and restarting the
application a lot.
When a message was sent to the JMS, when the sequence count was 100, the
entity threw a
java.sql.SQLException: ORA-00001: unique constraint violated
Which is correct, but because this message was rolled back, the message
was returned back to the queue and tried again. This again failed and
this result repeated itself. This obviously hammered the DB and
virtually ground it to a halt.
The first thing is where/how can I configure glassfish to set the retry
limit. At the moment I am manually seeing if the message has been
redelivered with getJMSRedelivered().
Secondly, why does toplink not throw away the invalid primary key and
then use 102. After further inspection, if I manually put any other row
into the DB, instead of the first one after the application has held 50,
ie not 101 but 103,104 etc , toplink tries to save the entity, throws
the exception and then uses the next number in the sequence.
So, if a row appears in the table with a primary key above the set
sequence count in the sequence table, toplink can handle this if it is
not the first one in the held memory count (i.e. not 51,101,151). This
means that either if I check redelivery and then leave the entity all
other messages sent to the queue will be left because toplink always
tries the invalid primary key or the message is constantly resent and
fails and hogs the DB.
I know that this row should have not appeared in the table higher than
the sequence count in the sequence table but I need to figure out
firstly why this happened, and secondly if I can stop toplink/glassfish
from trying the same invalid PK if this happens again.
Thanks Glen