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)

Here's the test I just ran using SQL Anywhere 12.0.1.3298. It shows that STOP SYNCHRONIZATION DELETE prevented 40 DELETE operations from being uploaded even though the COMMIT preceded the START SYNCHRONIZATION DELETE.

"%SQLANY12%bin32dbinit.exe" cons.db

"%SQLANY12%bin32dbspawn.exe" -f "%SQLANY12%bin32dbeng12.exe" -o dbeng12_log_cons.txt -os 1M -x none cons.db 
"%SQLANY12%bin32dbisql.com" -c "ENG=cons;DBN=cons;UID=dba;PWD=sql" READ ENCODING Cp1252 "%SQLANY12%MobiLinksetupsyncsa.sql"
PAUSE
"%SQLANY12%bin32dbisql.com" -c "ENG=cons;DBN=cons;UID=dba;PWD=sql" READ ENCODING Cp1252 001s_script_to_setup_cons.sql
PAUSE
REM Use bin32 if running on 32-bit Windows...
"%SQLANY12%bin64dbdsn.exe" -ws cons -y -c "ENG=cons;DBN=cons;UID=dba;PWD=sql"
PAUSE
"%SQLANY12%bin32dbinit.exe" remo.db
"%SQLANY12%bin32dbspawn.exe" -f "%SQLANY12%bin32dbeng12.exe" -o dbeng12_log_remo.txt -os 1M -x none remo.db 
"%SQLANY12%bin32dbisql.com" -c "ENG=remo;DBN=remo;UID=dba;PWD=sql" READ ENCODING Cp1252 001s_script_to_setup_remo.sql
PAUSE
"%SQLANY12%bin32dbisql.com" -c "ENG=cons;DBN=cons;UID=dba;PWD=sql"
"%SQLANY12%bin32dbisql.com" -c "ENG=remo;DBN=remo;UID=dba;PWD=sql"
PAUSE All done...

-- Define GLOBAL AUTOINCREMENT partition number.
SET OPTION PUBLIC.GLOBAL_DATABASE_ID = '0';

BEGIN
   DROP TABLE d;
   EXCEPTION WHEN OTHERS THEN
END;
CREATE TABLE d (
   key_1         UNSIGNED BIGINT NOT NULL 
                    DEFAULT GLOBAL AUTOINCREMENT ( 1000000000 ),
   non_key_1     VARCHAR ( 100 ) NOT NULL DEFAULT '',
   last_updated  TIMESTAMP NOT NULL DEFAULT TIMESTAMP,
   PRIMARY KEY ( key_1 ) );

CALL ml_add_table_script  ( 'v1', 'd', 'upload_insert', NULL );
CALL ml_add_table_script  ( 'v1', 'd', 'upload_insert', '
INSERT d
       ( key_1,
         non_key_1 )
VALUES ( ?,
         ? )' );

CALL ml_add_table_script  ( 'v1', 'd', 'upload_update', NULL );
CALL ml_add_table_script  ( 'v1', 'd', 'upload_update', '
UPDATE d
   SET non_key_1 = ?
 WHERE key_1 = ?' );

CALL ml_add_table_script  ( 'v1', 'd', 'upload_delete', NULL );
CALL ml_add_table_script  ( 'v1', 'd', 'upload_delete', '
DELETE d
 WHERE key_1 = ?' );

CALL ml_add_table_script  ( 'v1', 'd', 'download_cursor', NULL );
CALL ml_add_table_script  ( 'v1', 'd', 'download_cursor', '
SELECT key_1,
       non_key_1
  FROM d
 WHERE last_updated >= ?' );

CALL ml_add_table_script  ( 'v1', 'd', 'download_delete_cursor', NULL );
CALL ml_add_table_script  ( 'v1', 'd', 'download_delete_cursor', '--{ml_ignore}' );

-- Insert rows to download and then delete.
BEGIN
DECLARE @rowcount INTEGER;
SET @rowcount = 1;
WHILE @rowcount <= 100 LOOP
   INSERT d VALUES ( DEFAULT, DEFAULT, DEFAULT );
   SET @rowcount = @rowcount + 1;
END LOOP;
COMMIT;
END;

-- Define GLOBAL AUTOINCREMENT partition number.
SET OPTION PUBLIC.GLOBAL_DATABASE_ID = '1';

BEGIN
   REVOKE CONNECT FROM REMOTE_DBA;
   EXCEPTION WHEN OTHERS THEN
END;
GRANT CONNECT TO REMOTE_DBA IDENTIFIED BY SQL;
GRANT REMOTE DBA TO REMOTE_DBA;

BEGIN
   DROP SYNCHRONIZATION SUBSCRIPTION TO p1 FOR "1";
   EXCEPTION WHEN OTHERS THEN
END;
BEGIN
   DROP SYNCHRONIZATION USER "1";
   EXCEPTION WHEN OTHERS THEN
END;
BEGIN
   DROP PUBLICATION p1;
   EXCEPTION WHEN OTHERS THEN
END;

BEGIN
   DROP TABLE d;
   EXCEPTION WHEN OTHERS THEN
END;
CREATE TABLE d (
   key_1         UNSIGNED BIGINT NOT NULL 
                    DEFAULT GLOBAL AUTOINCREMENT ( 1000000000 ),
   non_key_1     VARCHAR ( 100 ) NOT NULL DEFAULT '',
   last_updated  TIMESTAMP NOT NULL DEFAULT TIMESTAMP,
   PRIMARY KEY ( key_1 ) );

CREATE PUBLICATION p1 (
   TABLE d  ( key_1,
              non_key_1 ) );
CREATE SYNCHRONIZATION USER "1" TYPE tcpip;
CREATE SYNCHRONIZATION SUBSCRIPTION TO p1 FOR "1";

"%SQLANY12%bin64mlsrv12.exe"^
  -c "DSN=cons;UID=dba;PWD=sql"^
  -o mlsrv12_log_cons.txt^
  -os 10M^
  -ppv 60^
  -vcefhkmnopstuU^
  -zu+ 

"%SQLANY12%bin32dbmlsync.exe"^
  -c "ENG=remo;DBN=remo;UID=REMOTE_DBA;PWD=SQL"^
  -e "adr='host=localhost';sv=v1"^
  -o dbmlsync_log_remo.txt^
  -os 10M^
  -vnosu^
  -x

-- Run initial sync.

-- Run this on remote database...
STOP SYNCHRONIZATION DELETE;
DELETE d WHERE key_1 <= 40;
COMMIT;
START SYNCHRONIZATION DELETE;

-- Run second sync.

-- Run this on consolidated database...
SELECT * FROM d;
key_1,non_key_1,last_updated
1,'','2012-05-08 08:42:21.104'
2,'','2012-05-08 08:42:21.137'
...
40,'','2012-05-08 08:42:21.140'
41,'','2012-05-08 08:42:21.140'
42,'','2012-05-08 08:42:21.140'
...
100,'','2012-05-08 08:42:21.143'