STOP SYNCHRONIZATION DELETE not working

[Former Member]

I am developing an iPad application with Client-Consolidated DB synchronization model. After synchronization I am performing a cleanup operation which deletes irrelevant records from client db. My cleanup procedure has 40 delete statements. The workflow for this cleanup is:
1. STOP SYNCHRONIZATION DELETE
2. Run all the delete queries.
3. COMMIT
4. START SYNCHRONIZATION DELETE
I have searched the documentation in which COMMIT is given after START SYNC command. I think it should not be the problem here.
I have tested this logic by executing through ULPreparedStatement::ExecuteStatement() and from the inbuilt C++ API function connection->stopSynchronizationDelete(). In both cases I am getting a true return value, but from the server log I can see that it is trying to upload those deletes to server.

[VolkerBarth]

Wild guess: AFAIK, MobiLink scripts should never do a COMMIT or ROLLBACK - cf. the warning from the docs:

Caution

There should be no implicit or explicit commit or rollback in your SQL synchronization scripts or the procedures or triggers that are called from your SQL synchronization scripts. COMMIT or ROLLBACK statements within SQL scripts alter the transactional nature of the synchronization steps. If you use them, MobiLink cannot guarantee the integrity of your data in the event of a failure.

[VolkerBarth]

Well, I may be wrong with my comment above, as the samples for STOP SYNCHRONIZATION DELETE surely do use a COMMIT, as you have stated yourself. Somewhat irritating...

[Former Member]

Stop Synchronization Delete happens on the remotes, and is not usually in the context of Sync. (At least I've never used it there, not sure, might be able to use it in some sp_hook procedures.) Anyway, that's why the COMMIT/ROLLBACK restrictions don't apply here. Sync scripts are most often used on the consolidated side.

I've been able to make this work under the normal db, but can't say I've tried it using UltraLite. I do notice that the documentation examples follow the pattern: STOP SYNCHRONIZATION DELETE; run the deletes -- no commit issued START SYNCHRONIZATION DELETE; COMMIT;

My usage has had the STOP, deletes, START in a sproc with the caller of the sproc calling the commit which matches the example patterns. I wouldn't have necessarily expected an extra commit to matter, but I could envision it being important. Might be worth a try.

[VolkerBarth]

Sorry, just forget about the non-sense I've written above - Ron has made the point clear: "Stop Synchronization Delete happens on the remotes", so my hints to the sync scripts on the cons are totally off-topic. - I won't delete my wrong comments, for the single reason that I believe one can learn something from wrong conclusions, as well..

[Breck_Carter]

Another wild guess: The COMMIT turns off the STOP SYNCHRONIZATION DELETE which then causes the deletes to be processed for upload. If so, this would fall into the category of undocumented bug, er, surprise, um, feature.

Here's a clue: the comment "-- including the stopping of the deletes" in the Help at http://dcx.sybase.com/index.html#1201/en/dbreference/start-synchronization-delete-statement.html implies that commit/rollback does have a direct effect on STOP SYNCHRONIZATION DELETE, and therefore should be executed after the START.

[Former Member · Accepted solution]

Hi Guys, Thanks a lot to all for their valuable comments, no matter they are just guesses but they gave me idea to work with a different approach which i was considering worthless. I tried it with the sequence though i have to do some code rearrangement and modification.
1) STOP SYNCHRONIZATION DELETE
2) DELETE
3) START SYNCHRONIZATION DELETE
4) COMMIT
and this worked just fine. I think Volker you are right, this COMMIT is affecting the behavior of STOP SYNC command and it seems applicable to remote DB too though you mentioned it off-topic. Special thanks to you for mentioning the same. You saved me.

[VolkerBarth · Accepted solution]

Glad you got it working - and feel free to "accept" your own answer.

For what I see, the credits w.r.t. COMMIT vs. STOP SYNC should go to Breck, not me:)

[Breck_Carter · Accepted solution]

The credit should go to Gandalf himself, who raised the issue in the original question and then discounted it: "... I have searched the documentation in which COMMIT is given after START SYNC command. I think it should not be the problem here."

I agree that "it should not be the problem" but life isn't always agreeable 🙂

[VolkerBarth · Accepted solution]

Well, in case it's "Gandalf the White", he won't need further credits:)

[Breck_Carter · Accepted solution]

Did you change more than one thing? ...because my test indicates that it doesn't matter whether the COMMIT is before or after the START SYNCHRONIZATION DELETE.

[Former Member · Accepted solution]

Hi Breck, I didn't change anything in sync model. Only the cleanup routine i rearranged. As in my solution i was performing all 40 DELETE statements required for me without committing them, then i START the sync and did the commit. this approach didn't upload any change happened due to DELETEs to consolidated database.
Can you please specify what kind of test you ran? Have you ran more than 1 deletes? If you run only one 1 delete it won't produce my scenario.

[Breck_Carter · Accepted solution]

I reran the test with 40 deletes and posted the code as a new answer.