It appears this problem depends on the size of transaction index.
Thanks Mark for the pointer.
The maximum number of lock objects needed can be estimated as follows:
For Btree and Recno access methods, you will need one lock object per level of the database tree, at a minimum. (Unless keys are quite large with respect to the page size, neither Recno nor Btree database trees should ever be deeper than five levels.) Then, you will need one lock object for each leaf page of the database tree that will be simultaneously accessed.
For the Queue access method, you will need one lock object per record that is simultaneously accessed. To this, add one lock object per page that will be simultaneously accessed. (Because the Queue access method uses fixed-length records and the database page size is known, it is possible to calculate the number of pages -- and, therefore, the lock objects -- required.) Deleted records skipped by a DB_NEXT or DB_PREV operation do not require a separate lock object. Further, if your application is using transactions, no database operation will ever use more than three lock objects at any time.
For the Hash access method, you only need a single lock object.
For all access methods, you should then add an additional lock object per database for the database's metadata page.
The maximum number of locks required by an application cannot be easily estimated. It is possible to calculate a maximum number of locks by multiplying the maximum number of lockers, times the maximum number of lock objects, times two (two for the two possible lock modes for each object, read and write). However, this is a pessimal value, and real applications are unlikely to actually need that many locks. Reviewing the Lock subsystem statistics is the best way to determine this value.
