[jira] [Updated] (IGNITE-13030) Calcite integration. Push projections to scans and avoid reading full row when possible

["Stanilovsky Evgeny (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-13030?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Stanilovsky Evgeny updated IGNITE-13030:
----------------------------------------
    Description: 
We can establish index-only scans in some cases. For example, if the column {{depId}} is indexed (and totally inlined), we can to execute a query like:
{code:java}
SELECT depId FROM emp
{code}

and collects resultset without pagememory lookups.
 

  was:
Currently {{IngiteTableScan}} supports only embedded filters. If it supports also embedded projections (see {{ProjectableFilterableTable}} in Calcite), it will be able to push these projections down to page memory scans in order to avoid full row reading.

For example for the query 

{code:java}
SELECT _val FROM tbl
{code}

we can read only values.

Moreover, we can establish index-only scans in some cases. For example, if the column {{depId}} is indexed, we can the execute query
{code:java}
SELECT depId FROM emp
{code}

using only index tree, without reading rows at all.
 


> Calcite integration. Push projections to scans and avoid reading full row when possible
> ---------------------------------------------------------------------------------------
>
>                 Key: IGNITE-13030
>                 URL: https://issues.apache.org/jira/browse/IGNITE-13030
>             Project: Ignite
>          Issue Type: Improvement
>          Components: sql
>            Reporter: Roman Kondakov
>            Priority: Minor
>
> We can establish index-only scans in some cases. For example, if the column {{depId}} is indexed (and totally inlined), we can to execute a query like:
> {code:java}
> SELECT depId FROM emp
> {code}
> and collects resultset without pagememory lookups.
>  



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