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https://issues.apache.org/jira/browse/DERBY-6942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16067124#comment-16067124
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Harshvardhan Gupta commented on DERBY-6942:
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In particular, when estimating cost for a particular conglomerate, it would be
good if we start looking at other conglomerates' statistics for cardinality
estimates. For example during table scan, we can start adjusting cardinality
estimates using the statistics for index.
Note that cost and cardinality are two different concepts, cost will always be
determined by the number and size of pages / rows that a particular access path
has to read to execute its work. Table scan's cost will remain unaffected here
in this case by changing thecardinality estimates. (However, index scan's cost
and cardinality estimates will be co-related in our particular example)
> Utilise additional statistics for selectivity estimates.
> --------------------------------------------------------
>
> Key: DERBY-6942
> URL: https://issues.apache.org/jira/browse/DERBY-6942
> Project: Derby
> Issue Type: Sub-task
> Components: SQL
> Reporter: Harshvardhan Gupta
> Assignee: Harshvardhan Gupta
> Priority: Minor
>
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