Lock escalation   To maintain data consistency between the consolidated and remote databases, the MobiLink server issues the following query through the ml_lock_rid stored procedure to lock the remote ID in every synchronization phase.

SELECT sync_key into p_sync_key FROM ml_database WHERE rid = a_given_remote_id WITH RR USE AND KEEP EXCLUSIVE LOCKS;

This query exclusively locks the remote ID to prevent any concurrent synchronizations using the same remote ID.

If you experience any MobiLink remote ID locking errors when there are no concurrent synchronizations for the same remote ID, for example, if MobiLink error code -10341 is in the MobiLink server log, you may need to adjust the DB2 maxlocks and locklist configuration parameters to prevent lock escalation. Consult the DB2 documentation for full details.

Data type mapping   The data types of columns must map correctly between your consolidated and remote database. For details, see IBM DB2 LUW data mapping.

CHAR columns   In IBM DB2 LUW, CHAR data types are fixed length and blank-padded to the full length of the string. In MobiLink remote databases (SQL Anywhere or UltraLite) CHAR is the same as VARCHAR: values are not blank-padded to a fixed width. It is strongly recommended that you use VARCHAR in the consolidated database rather than CHAR. If you must use CHAR, the mlsrv16 -b command line option can be used to remove trailing blanks from strings during synchronization. This option is important for string comparisons used to detect conflicts.

See -b mlsrv16 option.

Tablespace capacity   A tablespace and temporary tablespace of any IBM DB2 LUW database that you want to use as a consolidated database must use at least 8 KB pages.

In addition, there are columns that require a LONG tablespace. If there is no default LONG tablespace, the creation statements for the tables containing these columns must be qualified appropriately, as in the following example:

CREATE TABLE ... ( ... )
IN tablespace
LONG IN long-tablespace

For an example using the sample application, see CustDB sample for MobiLink.

Double up the quotation marks in system procedure calls   When you use a MobiLink system procedure to add scripts to your IBM DB2 consolidated database, you need to double up the quotation marks. For example, if the script you are adding with ml_add_table_script includes the line SET "DELETED"=''Y'' for any other consolidated database, for IBM DB2 you would have to write this as SET "DELETED" = ''''Y''''.