Michael Smith created IMPALA-13166:
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Summary: 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
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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