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dc.contributor.authorNeumann, T
dc.contributor.authorHelmer, S
dc.contributor.authorMoerkotte, G
dc.description.abstractWe examine the problem of producing the optimal evaluation order for queries containing joins, selections, and maps. Specifically, we look at the case where common subexpressions involving expensive UDF calls can be factored out. First, we show that ignoring factorization during optimization can lead to plans that are far off the best possible plan: the difference in cost between the best plan considering factorization and the best plan not considering factorization can easily reach several orders of magnitude. Then, we introduce optimization strategies that produce optimal left-deep and bushy plans when factorization is taken into account. Experiments (1) confirm that factorization is a critical issue when it comes to generating optimal plans and (2) we show that to consider factorization does not make plan generation significantly more expensive
dc.relation.ispartofseriesProceedings / International Conference on Data Engineering;
dc.relation.ispartofseriesProceedings / International Conference on Data Engineering
dc.titleOn the optimal ordering of maps and selections under factorization
dc.typeBook chapter
dc.publication.titleProceedings 21st International Conference on Data Engineering ; ICDE 2005 ; 5. - 8. April 2005, National Center of Science, Tokyo, Japan
dc.journal.titleProceedings / International Conference on Data Engineering

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