STOP SYNCHRONIZATION DELETE not working

[VolkerBarth]

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_SQLA_member1694876]

Sorry Guys, but the order of 'commit' and 'start sync delete' statements doesn't make any difference. Nor does 'commit' reset or affect the stop-sync-delete status/flag. All that matters is which delete-mode is in effect when the delete statement itself is executed. (This is a little better than a wild guess, hopefully, since I've checked the code 😉

So, I'm afraid something more is going on here.

What sometimes does cause confusion with stop-sync-delete is the following sequence:

• insert a row
• stop sync delete
• delete that row
• start sync delete
• synchronize

What will be uploaded on the synchronize? The delete will not of course, but the insert of the row will. This is different than the following, where nothing is uploaded on the final synchronize:

• insert a row
• synchronize (uploads that new row)
• stop sync delete
• delete that row
• start sync delete
• synchronize

The other normal cases are:

• insert a row
• delete that row (no stop-sync-delete here)
• synchronize (nothing goes up)

and

• insert a row
• synchronize (uploads the insert)
• delete that row
• synchronize (uploads the delete)

[Breck_Carter]

...and we know that "reading the code" beats "testing the code" every time, right? <bg>

[Breck_Carter]

...and a test using 12.0.1.3298 does agree with Tim's reading of the code: it doesn't matter where the COMMIT goes, before or after the START SYNCHRONIZATION DELETE; either way, the row deleted on the remote database after the STOP SYNCHRONIZATION DELETE is not deleted from the consolidated.

[former_SQLA_member1694876]

🙂

(Truth be told I'm old enough that I did indeed monkey around a bit with a test as well before posting... But there's only so much time you know... 😉