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https://issues.apache.org/jira/browse/IMPALA-13166?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18053733#comment-18053733
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ASF subversion and git services commented on IMPALA-13166:
----------------------------------------------------------
Commit bedc586036e9554beb63c39ac47d2f024039fbf5 in impala's branch
refs/heads/master from Michael Smith
[ https://gitbox.apache.org/repos/asf?p=impala.git;h=bedc58603 ]
IMPALA-13166: Cache hashCode
Precomputes the hashCode when populating fullyQualifiedRawPath_ to
minimize hashCode recomputations.
Speeds up PlannerTest#testManyExpressionPerformance by a small amount
(<5%) in local testing.
Change-Id: Ia4141be3e5e4e1ba8bac0b3fc3631e0e71e33ec0
Reviewed-on: http://gerrit.cloudera.org:8080/21532
Reviewed-by: Michael Smith <[email protected]>
Tested-by: Michael Smith <[email protected]>
> Queries with many nested views are still slow
> ---------------------------------------------
>
> Key: IMPALA-13166
> URL: https://issues.apache.org/jira/browse/IMPALA-13166
> Project: IMPALA
> Issue Type: Improvement
> Components: Frontend
> Affects Versions: Impala 4.4.0
> Reporter: Michael Smith
> Assignee: Michael Smith
> Priority: Critical
> Fix For: Impala 5.0.0
>
>
> Further profiling on the query from IMPALA-12800 - and a larger version of
> the same - show significant time spent in {{Analyzer#registerSlotRef}}. The
> bulk of the work here is in checking whether a {{SlotDescriptor}} exists in
> the current {{TupleDescriptor}}, both because
> {{Path#getFullyQualifiedRawPath}} is expensive and because equals on the
> resulting list is expensive (especially repeated over every
> {{SlotDescriptor}} in the {{TupleDescriptor}}.
> There's room for improvement here:
> 1. avoid copying {{rawPath_}} every time we call {{getFullyQualifiedRawPath}}
> 2. use a map to identify whether a {{SlotDescriptor}} already exists at
> {{Path}} in the current {{TupleDescriptor}}
> 3 other small improvements may exist around memory allocation
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