[
https://issues.apache.org/jira/browse/CALCITE-4511?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17289709#comment-17289709
]
Julian Hyde edited comment on CALCITE-4511 at 2/24/21, 6:57 AM:
----------------------------------------------------------------
Please change this case subject and the commit message to use Calcite's
terminology, not NDV. This enhancement applies to both PopulationSize and
DistinctRowCount. Can you please fix (and test) both?
was (Author: julianhyde):
Please change this case subject and the commit message to use Calcite's
terminology, not NDV.
> The number of distinct values for constant columns should be 1
> --------------------------------------------------------------
>
> Key: CALCITE-4511
> URL: https://issues.apache.org/jira/browse/CALCITE-4511
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Liya Fan
> Assignee: Liya Fan
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Suppose we have a relation with 3 columns: {{(a, '1', '2')}}. The first
> column comes from an underlying table, while the other two columns are
> constants.
> For this relation, we should have {{NDV(1) = 1}}, since column 1 is a
> constant, which have only one possible value (suppose the column index starts
> from 0).
> Similarly, we should have {{NDV(1, 2) = 1}}, since both columns are constants.
> We should also have {{NDV(0, 1) == NDV(0)}}, because the number of distinct
> values depends on the non-const column, which is {{a}} from the underlying
> table.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
