Distributed set-expression cardinality estimation
AssigneeAlcatel-Lucent USA Inc.
InventorsAbhinandan Das, Sumit Ganguly, Minos Garofalakis, Rajeev Rastogi
Life of this patent
Estimating the term…
Abstract
A method and system for answering set-expression cardinality queries while lowering data communication costs by utilizing a coordinator site to provide global knowledge of the distribution of certain frequently occurring stream elements to significantly reduce the transmission of element state information to the central site and, optionally, capturing the semantics of the input set expression in a Boolean logic formula and using models of the formula to determine whether an element state change at a remote site can affect the set expression result.
Claims22
In a system adapted to receive update streams from a plurality of update stream sites, a method comprising:
- establishing, for each of said update stream sites, a respective site charge budget;
- and
- communicating said site charge budgets toward said update stream sites;
- each site charge budget being adapted to control an initiation of update stream transmission by restricting transmission of said update stream until a sum of element charges at the respective update stream site exceeds the site charge budget, said element charges being attributed to stream element updates.
A distributed framework for providing a set expression estimation, comprising:
- allocating error budgets to each of a plurality of remote sites according to a first set of invariants, each of said remote sites providing a respective update stream to a coordinator site, said update streams including at least one of insert elements and delete elements;
- and
- allocating update stream insert element and delete element charges according to a second set of invariants;
- wherein
- each of said remote sites accumulating element charges in response to the occurrence of respective update and delete elements;
- each of said remote sites transmitting a respective update stream to said coordinator site when an accumulation of element charges exceeds a respective error budget.
A distributed framework for processing set-expression cardinality queries, wherein:
- each update stream site being allocated an error budget adapted to determine when the update stream site communicates stream state information to a central site;
- each update stream site associates a charge with every stream element that is inserted or deleted since stream state was previously transmitted to a central site;
- each update stream site transmits current stream state information when the sum of its respective element charges exceeds its respective error budget.
Dependencies are inferred from the claim text.