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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