[
https://issues.apache.org/jira/browse/CALCITE-4351?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
ASF GitHub Bot updated CALCITE-4351:
------------------------------------
Labels: pull-request-available (was: )
> RelMdUtil#numDistinctVals always returns 0 for large inputs
> -----------------------------------------------------------
>
> Key: CALCITE-4351
> URL: https://issues.apache.org/jira/browse/CALCITE-4351
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.26.0
> Reporter: Caizhi Weng
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Previous implementation of {{RelMdUtil#numDistinctVals}} uses the
> approximation {{ln(1 + x) ~= x}} when {{x}} is small.
> However CALCITE-4132 remove this approximation to make the result more
> accurate. This causes the function to calculate an incorrect result for large
> inputs (for example, when {{domainSize = 1e18}} and {{numSelected = 1e10}}
> the result is 0) due to precision problems.
> What I would suggest is to treat small and large inputs in different ways.
> For small inputs we use the new, more precise function and for large inputs
> we use the old, approximated function.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
