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https://issues.apache.org/jira/browse/IGNITE-13026?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Taras Ledkov reassigned IGNITE-13026:
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Assignee: Taras Ledkov
> Calcite integration. Fix metadata for IgniteTable when it has embedded
> filters.
> -------------------------------------------------------------------------------
>
> Key: IGNITE-13026
> URL: https://issues.apache.org/jira/browse/IGNITE-13026
> Project: Ignite
> Issue Type: Bug
> Components: sql
> Reporter: Roman Kondakov
> Assignee: Taras Ledkov
> Priority: Major
>
> By default {{RelMdRowCount}} return the actual row count for
> {{IgniteTables}}. But current implementation of {{IgniteTableScan}} may
> contain embedded filters and rows that are filtered out by these filters are
> not taken into account by the metadata subsystem.
> For example, table emps contains 1000 rows. Filter name='Vasya' filters out
> 95% of rows. For now we end up with situation
> {code:java}
> IgniteFilter(name='Vasya') <- estimated cardinality = 50 rows
> IgniteTableScan(filters=null) <- estimated cardinality = 1000 rows.
> {code}
> but after merging {{Filter}} into {{Scan}} we get the wrong estimation
> {code:java}
> IgniteTableScan(filters={name='Vasya'}) <- estimated cardinality = 1000 rows.
> But should be 50 rows.
> {code}
> We need to add a special case in order to compute the actual cardinality
> returned by {{IgniteTableScan}}
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