Analyzing Plan Diagrams of Database Query Optimizers

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Analyzing Plan Diagrams of Database Query Optimizers
A “plan diagram” is a pictorial enumeration of the execution plan choices of a database query optimizer over the relational selectivity space. In this paper, we present and analyze representative plan diagrams on a suite of popular commercial query optimizers for queries based on the TPC-H benchmark. These diagrams, which often appear similar to cubist paintings, provide a variety of interesting insights, including that current optimizers make extremely fine-grained plan choices, which may often be supplanted by less efficient options without substantively affecting the quality; that the plan optimality regions may have highly intricate patterns and irregular boundaries, indicating strongly non-linear cost models; that nonmonotonic cost behavior exists where increasing result cardinalities decrease the estimated cost; and, that the basic assumptions underlying the research literature on parametric query optimization often do not hold in practice.
Naveen Reddy, Jayant R. Haritsa
Added 28 Jun 2010
Updated 28 Jun 2010
Type Conference
Year 2005
Where VLDB
Authors Naveen Reddy, Jayant R. Haritsa
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