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From Dmitriy Setrakyan <dsetrak...@apache.org>
Subject Re: EXPLAIN for DML statements
Date Tue, 27 Dec 2016 05:56:11 GMT
I agree. I also would very much like to see the support of "Explain" for
DML statements. Is there some limitation in H2 that prevents us from
supporting it?

On Fri, Dec 23, 2016 at 10:36 AM, Denis Magda <dmagda@apache.org> wrote:

> This might be a tricky part for the users because they need to recreate
> the query manually
>
> > UPDATE Person SET name = 'John' WHERE surname = 'Smith',
> >
> > then we could show
> >
> > EXPLAIN SELECT _key from Person WHERE surname = 'Smith’;
>
> How difficult is to support EXPLAIN for DML in general? Let’s discuss the
> challenges and implementation details and create a ticket after that.
>
> —
> Denis
>
>
> > On Dec 23, 2016, at 7:46 AM, Alexander Paschenko <
> alexander.a.paschenko@gmail.com> wrote:
> >
> > Denis,
> >
> > Currently there's no API to get those queries. However, they are
> > always generated under the hood - except for 'fast' UPDATE and DELETE
> > that don't need any queries.
> > So what is suggested in docs is to EXPLAIN those SELECTs - say, if we
> > have DML statement
> >
> > UPDATE Person SET name = 'John' WHERE surname = 'Smith',
> >
> > then we could show
> >
> > EXPLAIN SELECT _key from Person WHERE surname = 'Smith';
> >
> > - Alex
> >
> > 2016-12-23 3:09 GMT+03:00 Denis Magda <dmagda@apache.org>:
> >> Alex P., Sergi,
> >>
> >> All we know that EXPLAIN is not supported for DML statements at the
> moment.
> >> http://apacheignite.gridgain.org/docs/dml#section-explain-
> support-for-dml-statements
> >>
> >> However, I can’t get how I can get over this limitation for UPDATE and
> >> DELETE statements following this recommendation
> >>
> >> "One possible approach is to execute EXPLAIN for the SELECT
> automatically
> >> generated (UPDATE, DELETE) or used (INSERT, MERGE) by DML statements.
> This
> >> will give an insight on the indexes that are used while a DML operation
> is
> >> executed.”
> >>
> >> How can I get SELECT queries that are generated by these DML operations
> >> automatically?
> >>
> >> —
> >> Denis
>
>

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