Jesus Camacho Rodriguez created HIVE-21867:
----------------------------------------------
Summary: Sort semijoin conditions to accelerate query processing
Key: HIVE-21867
URL: https://issues.apache.org/jira/browse/HIVE-21867
Project: Hive
Issue Type: Bug
Components: CBO
Reporter: Jesus Camacho Rodriguez
Assignee: Jesus Camacho Rodriguez
Following approach similar to
http://db.cs.berkeley.edu/jmh/miscpapers/sigmod93.pdf .
To reorder predicates in AND conditions, we could rank each of elements in the
clauses in increasing order based on following formula:
{code}
rank = (selectivity - 1) / cost per tuple
{code}
Similarly, for OR conditions:
{code}
rank = (-selectivity) / cost per tuple
{code}
Selectivity can be computed with FilterSelectivityEstimator. For cost per
tuple, we will need to come up with some heuristic based on how expensive is
the evaluation of the functions contained in that predicate. Custom UDFs could
be annotated.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
