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Posted to issues@ignite.apache.org by "Vladimir Steshin (Jira)" <ji...@apache.org> on 2022/05/18 13:57:00 UTC
[jira] [Commented] (IGNITE-16920) Calcite Engine. COUNT() lacks optimization.
[ https://issues.apache.org/jira/browse/IGNITE-16920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17538856#comment-17538856 ]
Vladimir Steshin commented on IGNITE-16920:
-------------------------------------------
Calcite doesn't use index, counting records in metapages like H2.
What H2 does:
{code:java}
H2TreeIndex:: getRowCount()
public long InlineIndexImpl::count(int segment, IndexQueryContext qryCtx) throws IgniteCheckedException {
return segments[segment].size(filterClosure(qryCtx));
}
metaPage -> records number
{code}
Calcite:
IgniteReduceHashAggregate(group=[{}], COUNT(*)=[COUNT()])
IgniteExchange(distribution=[single])
IgniteMapHashAggregate(group=[{}], COUNT(*)=[COUNT()])
IgniteTableScan(table=[[PUBLIC, PI_COM_DAY]])
> Calcite Engine. COUNT() lacks optimization.
> -------------------------------------------
>
> Key: IGNITE-16920
> URL: https://issues.apache.org/jira/browse/IGNITE-16920
> Project: Ignite
> Issue Type: Improvement
> Components: sql
> Affects Versions: 2.13
> Reporter: YuJue Li
> Priority: Major
> Labels: calcite2-required, calcite3-required
> Fix For: 2.14
>
> Attachments: PI_COM_DAY.sql, example-calcite.xml, image-2022-05-01-13-35-59-275.png
>
>
> !image-2022-05-01-13-35-59-275.png!
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