Decapsulation:
Estimating Execution Profiles in Object Bases
Authors:
- Donald Kossmann
- Michael Steinbrunn
- Alfons Kemper
Date:
- Feb. 1993, RWTH Aachen
Abstract:
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In this paper, we propose a novel method - called decapsulation -
for statically estimating the (running time) cost of object base
application programs. The approach is based on extracting weighted
inter-object reference chains that are potentially traversed during
the execution of the program. These reference chains, called
path expressions at the syntactical level, are obtained by
data flow analysis; the weights, which denote the traversal
probability, are derived from selectivity estimates of the branching statements,
i.e., the If-statements. From the inter-object
reference profile thus obtained, a Petri net based simulation of the
application program is derived. The Petri net is initialized by the
object base characteristics, such as the cardinality of the relevant
type extensions, the fan-in and fan-out of the objects, etc. The
outcome of the simulation constitutes an estimate of the I/O
costs, i.e., the number of (different) objects read by the program.
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Uwe Röhm, 08.06.1994; Last Change: 07.11.94