can i use ORA_ROWSCN to handle concurrency in oracle, That is i want to read ora_rowscn and keep it in my form or BL then before update i want to read ora_rowscn and match with old version.
1)Since it is updated after commit , how can it affect the application?
2) should i use some Guid in place of ORA_ROWSCN?
3) sequence in each table with trigger in place of ORA_ROWSCN?
I am running Oracle RAC 2 nodes 11g R2 on AIX 7.1
I have a table with unique index, and the application is doing inserts/updates into this table.Suddenly and for about half a minute I faced a high concurrency waits on all the processes running these inserts for one node. I saw this high concurrency wait in the top activity screen of the OEM only on one of the nodes. knowing that the processes doing these inserts are running on both nodes.
All what I have that in this half minute I see high concurrency wait in OEM top activity screen related to this insert statement and when I clicked on the insert I found high "enq: TX - index contention". Again this was only on one node.After this half minute everything went back to normal.What could be the reason and how can I investigate it ?
When running into what should be an OptimisticConcurrencyException in entity framework, i'm getting an update exception as follows:
"A null store-generated value was returned for a non-nullable member 'DateChanged' of type 'FDDT.Model.FeedArray'."
I'm using the DateChanged field as the concurrency tracking field. In entity framework DateChanged has the following properties:
StoreGeneratedPattern: Computed
Concurrency Mode: Fixed
I have a trigger set on this field as follows:
TRIGGER FEED_ARRAY_TRIG_DTCHG before update on FEED_ARRAY for each row
begin
:new.DATE_CHANGED := sysdate;
end;
I've tried setting this concurrency tracking field to "Identity" instead, however that causes another error when I run into a concurrency exception and refresh using the client wins option.
Most of my day to day work involves the support of DB2 on AIX and z/OS. I support the database infrastructure for one business system that runs on the Oracle RDBMS. The application is Oracle Transportation Management. The non-production environments don't get much traffic. If I sign into the TEST or DEV Enterprise Manager DB Control screen, the following warning is almost always listed on the main page:
Metrics "Database Time Spent Waiting (%)" is at 44.00384 for event class "Concurrency"
Enterprise Manager reports that this metric is continuously fluctuating above and below the warning threshold of 30% of db time when the environment is idle.To investigate(and I am no oracle expert, far from it), I ran the following:
SELECT * FROM v$session_event
WHERE WAIT_CLASS='Concurrency'
ORDER BY TOTAL_WAITS DESC;
By far, the top two entries in the result are the following:
SIDEVENTTOTAL_WAITSTIME_WAITEDAVERAGE_WAITMAX_WAIT
124os thread startup12041423733.5218
359os thread startup150653433.5521
[code]...
Does this indicate a possible problem with the operating system?