InventSumDelta表的作用

https://groups.google.com/forum/#!topic/microsoft.public.axapta.programming/rRfbJo9M0dk

The purpose of the InventSumDelta table is to avoid locking on the InventSum
table. During a transaction all inventory movements will be recorded in the
InventSumDelta table (i.e. when InventTrans is inserted or updated). When the
transaction is to be commited the method Application::ttsNotifyPreCommit is
called and the contents of InventSumDelta is added to the relevant InventSum
records. This replaces the IMTS in Ax 3.0 and 2.5 (sp?)
This avoids locking InventSum until the very last moment.

So, you can use InventSumDelta whenever the
on-hand may be changed in the same transaction as the calling code.