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https://issues.apache.org/jira/browse/IGNITE-21372?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Maksim Zhuravkov updated IGNITE-21372:
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Summary: Sql. Do not execute queries that guaranteed to return no results.
(was: Sql. Do not execute queries that guaranteed to return none results.)
> Sql. Do not execute queries that guaranteed to return no results.
> -----------------------------------------------------------------
>
> Key: IGNITE-21372
> URL: https://issues.apache.org/jira/browse/IGNITE-21372
> Project: Ignite
> Issue Type: Improvement
> Components: sql
> Affects Versions: 3.0.0-beta2
> Reporter: Maksim Zhuravkov
> Priority: Minor
>
> {code:java}
> sql("CREATE TABLE t2 (id INTEGER PRIMARY KEY, val INTEGER)");
> // Query that never returns a result:
> sql("SELECT * FROM t2 WHERE id IS NULL");
> // Plan
> IgniteExchange(distribution=[single]): rowcount = 2500.0, cumulative cost =
> IgniteCost [rowCount=12500.0, cpu=42500.0, memory=0.0, io=0.0,
> network=20000.0], id = 28
> IgniteTableScan(table=[[PUBLIC, T2]], tableId=[8], *filters=[false]*,
> requiredColumns=[{0, 1}]): rowcount = 2500.0, cumulative cost = IgniteCost
> [rowCount=10000.0, cpu=40000.0, memory=0.0, io=0.0, network=0.0], id = 25
> {code}
> Although the optimizer is able deduce that `id is NULL` is always false,
> since id is not nullable, and converted a predicate FALSE, the execution
> engine still runs such a query.
> It is possible reduce plans that are guaranteed to produce no results to some
> form of an empty plan, so that the execution engine won't run them and return
> an empty cursor instead.
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