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https://issues.apache.org/jira/browse/IGNITE-16920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17538856#comment-17538856
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Vladimir Steshin edited comment on IGNITE-16920 at 5/18/22 2:02 PM:
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Calcite doesn't use index like H2. There is IGNITE-13919 already.
*H2:*
{code:java}
H2TreeIndex::getRowCount()
public long InlineIndexImpl::count(int segment, IndexQueryContext qryCtx)
throws IgniteCheckedException {
return segments[segment].size(filterClosure(qryCtx));
}
metaPage -> records number
{code}
And sums the counts from the index segments.
*Calcite:*
{code:java}
IgniteReduceHashAggregate(group=[{}], COUNT(*)=[COUNT()])
IgniteExchange(distribution=[single])
IgniteMapHashAggregate(group=[{}], COUNT(*)=[COUNT()])
IgniteTableScan(table=[[PUBLIC, PI_COM_DAY]])
{code}
was (Author: vladsz83):
Calcite doesn't use index, counting records in metapages like H2. There is
IGNITE-13919 already.
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}
And sums the counts from the index segments.
Calcite:
{code:java}
IgniteReduceHashAggregate(group=[{}], COUNT(*)=[COUNT()])
IgniteExchange(distribution=[single])
IgniteMapHashAggregate(group=[{}], COUNT(*)=[COUNT()])
IgniteTableScan(table=[[PUBLIC, PI_COM_DAY]])
{code}
> 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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