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

["Roman Kondakov (Jira)" <ji...@apache.org>]

Roman Kondakov created IGNITE-13030:
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             Summary: 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


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.
 



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