Ioana Delaney created SPARK-20233:
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Summary: Apply star-join filter heuristics to dynamic programming
join enumeration
Key: SPARK-20233
URL: https://issues.apache.org/jira/browse/SPARK-20233
Project: Spark
Issue Type: Sub-task
Components: SQL
Affects Versions: 2.2.0
Reporter: Ioana Delaney
Priority: Critical
This JIRA integrates star-join detection with the cost-based optimizer.
The join enumeration using dynamic programming generates a set of feasible
joins. The sub-optimal plans can be eliminated by a sequence of independent,
optional filters. The optional filters include heuristics for reducing the
search space. For example,
# Star-join: Tables in a star schema relationship are planned together since
they are assumed to have an optimal execution.
# Cartesian products: Cartesian products are deferred as late as possible to
avoid large intermediate results (expanding joins, in general).
# Composite inners: “Bushy tree” plans are not generated to avoid materializing
intermediate result.
For reference, see “Measuring the Complexity of Join Enumeration in Query
Optimization” by Ono et al.
This JIRA implements the star join filter.
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