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https://issues.apache.org/jira/browse/IGNITE-23430?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Maksim Zhuravkov reassigned IGNITE-23430:
-----------------------------------------
Assignee: Maksim Zhuravkov
> Sql. Provide an ability to cancel query before first page ready
> ---------------------------------------------------------------
>
> Key: IGNITE-23430
> URL: https://issues.apache.org/jira/browse/IGNITE-23430
> Project: Ignite
> Issue Type: Improvement
> Components: sql
> Reporter: Konstantin Orlov
> Assignee: Maksim Zhuravkov
> Priority: Major
> Labels: ignite-3
>
> Currently, the only possible way to cancel a query prematurely is by invoking
> {{cancel()}} on a {{ResultSet}} object. The problem is the result set is
> returned only when first page is ready. For statements like DML and DDL this
> means that result set will be returned only when operation is complete.
> Proposed solution is to introduce new pair of entities to public API:
> {code:java}
> /**
> * A handle which may be used to request the cancellation of execution.
> */
> public interface CancelHandle {
> /** A factory method to create a handle. */
> static CancelHandle create() {}
> /**
> * Abruptly terminates an execution of an associated process.
> *
> * <p>Control flow will return after the process has been terminated and
> the resources associated with that process have been freed.
> */
> void cancel();
> /**
> * Abruptly terminates an execution of a associated process.
> *
> * @return A future that will be completed after the process has been
> terminated and the resources associated with that process have
> * been freed.
> */
> CompletableFuture<Void> cancelAsync();
> /**
> * Flag indicating whether cancellation was requested or not.
> *
> * <p>This method will return true even if cancellation has not been
> completed yet.
> *
> * @return {@code true} when cancellation was requested.
> */
> boolean isCancelled();
> /**
> * Issue a token associated with this handle.
> *
> * <p>Token is reusable, meaning the same token may be used to link
> several executions into a single cancellable.
> */
> CancellationToken token();
> }
> public interface CancellationToken { }
> {code}
> Also, a new group of {{execute<*>}} methods accepting optional
> {{CancellationToken}} parameter must be introduced to sql facade:
> {code:java}
> public interface IgniteSql {
> <...>
>
> ResultSet<SqlRow> execute(
> @Nullable Transaction transaction,
> @Nullable CancellationToken cancellationToken,
> String query,
> @Nullable Object... arguments
> );
>
> <...>
> }
> {code}
> When user need a better control over query lifecycle, they should create
> handle and propagate token to the execution:
> {code:java}
> IgniteSql sql = <acquire sql api>;
> // create cancellation handle
> CancelHandle handle = CancelHandle.create();
> // propagate cancellation token to an execution
> sql.executeAsync(null, handle.token(), "<query text>");
> // propagate token from the same handle to more executions, if needed
> sql.executeAsync(null, handle.token(), "<query text>");
> // cancel everything at once
> handle.cancel();
> {code}
> Definition of Done: new entities are introduced to public API and integrated
> with single statement execution flow from embedded API.
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