In this paper, we have proposed improved concurrency control protocol based on speculation for nested transuctions and explained how it increases both intra-and intertransaction concurrency as compared to Mo.s.s's nested locking protocol. I n the proposed speculative nested locking (SNL) protocol, whenever a sub-trunsuctinn finishes work with a data object (produces after-image), it's purent inherits the lock. The waiting sub-transaction curries nut speculutive executions by accessing both

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... eund after-images of preceding sub-transaction and selects appropriate execution after the termination of preceding subtransaction. In this way, SNL allows multiple executions to be curried out for a trunsuction by trading extru processing and main niemoty resources to increuse concurrency.