The whole point of Transformer is to do remote transform, how will this
work with SqlFieldsQuery? What you are going to transform remotely here? I
believe all the transformations must happen at SQL level here.
Sergi
2016-02-04 20:10 GMT+03:00 Andrey Gura <ag...@gridgain.com>:
> SqlQuery, TextQuery and SpiQuery are similar to ScanQuery because all of
> them also defined as Query<Cache.Entry<>>.
>
> It can be usefull to have one query SqlQuery that can return different
> result that will be produced from cache entry by transformer.
>
> Actually only SqlFieldsQuery has different definition. So transformers can
> be applied to any type of query (including SqlFieldsQuery, I believe).
>
> On Thu, Feb 4, 2016 at 7:42 PM, Sergi Vladykin <sergi.vlady...@gmail.com>
> wrote:
>
> > I don't like the idea of having additional method *query(Query<E> qry,
> > Transformer<E, R> transfomer); *because I don't see how these
> transformers
> > will work for example with SQL, but this API makes you think that
> > transformers are supported for all the query types.
> >
> > Sergi
> >
> > 2016-02-04 16:46 GMT+03:00 Andrey Gura <ag...@gridgain.com>:
> >
> > > Val,
> > >
> > > can we introduce new method into IgnteCache API?
> > >
> > > Now we have method: public <R> QueryCursor<R> query(Query<R> qry);
> > >
> > > New method will be something like this: <R> QueryCursor<R>
> query(Query<E>
> > > qry, Transformer<E, R> transfomer);
> > >
> > > It allows provide transformers for all query types and chnages will be
> > > related only with query cursor functionality.
> > >
> > > Will it work?
> > >
> > > On Thu, Feb 4, 2016 at 11:13 AM, Andrey Kornev <
> andrewkor...@hotmail.com
> > >
> > > wrote:
> > >
> > > > Another perhaps bigger problem with running queries (including scan
> > > > queries) using closures was discussed at length on the @dev not so
> long
> > > > ago. It has to do with partitions migration due to cluster topology
> > > changes
> > > > which may result in the query returning incomplete result. And while
> it
> > > is
> > > > possible to solve this problem for the scan queries by using some
> > clever
> > > > tricks, all bets are off with the SQL queries.Andrey
> > > > _____________________________
> > > > From: Valentin Kulichenko <valentin.kuliche...@gmail.com>
> > > > Sent: Thursday, February 4, 2016 6:29 AM
> > > > Subject: Re: Transformers in SCAN queries
> > > > To: <dev@ignite.apache.org>
> > > >
> > > >
> > > > Dmitry,
> > > >
> > > > The main difference in my view is that you lose pagination when
> > sending
> > > > results from servers to client. What if one wants to iterate through
> > all
> > > > entries in cache?
> > > >
> > > > On Wed, Feb 3, 2016 at 9:47 PM, Dmitriy Setrakyan <
> > > dsetrak...@apache.org>
> > > > wrote:
> > > >
> > > > > Valentin,
> > > > >
> > > > > Wouldn’t the same effect be achieved by broadcasting a closure to
> > the
> > > > > cluster and executing scan-query on every node locally?
> > > > >
> > > > > D.
> > > > >
> > > > > On Wed, Feb 3, 2016 at 9:17 PM, Valentin Kulichenko <
> > > > > valentin.kuliche...@gmail.com> wrote:
> > > > >
> > > > > > Igniters,
> > > > > >
> > > > > > I keep getting requests from our users to add optional
> > transformers
> > > to
> > > > > SCAN
> > > > > > queries. This will allow to iterate through cache, but do not
> > > transfer
> > > > > > whole key-value pairs across networks (e.g., get only keys). The
> > > > feature
> > > > > > looks useful and I created a ticket [1].
> > > > > >
> > > > > > I am struggling with the design now. The problem is that I
> wanted
> > to
> > > > > extend
> > > > > > existing ScanQuery object for this, but this seems to be
> > impossible
> > > > > because
> > > > > > it already extends Query<Cache.Entry<K, V>> and thus can iterate
> > > only
> > > > > > through entries.
> > > > > >
> > > > > > The only option I see now is to create a separate query type,
> > > > copy-paste
> > > > > > everything from ScanQuery and add *mandatory* transformer.
> > Something
> > > > like
> > > > > > this:
> > > > > >
> > > > > > ScanTransformQuery<K, V, R> extends Query<R> {
> > > > > > IgniteBiPredicate<K, V> filter;
> > > > > > IgniteClosure<Cache.Entry<K, V>, R> transformer;
> > > > > > int part;
> > > > > > ...
> > > > > > }
> > > > > >
> > > > > > Thoughts? Does anyone has other ideas?
> > > > > >
> > > > > > [1] https://issues.apache.org/jira/browse/IGNITE-2546
> > > > > >
> > > > > > -Val
> > > > > >
> > > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >
> > > --
> > > Andrey Gura
> > > GridGain Systems, Inc.
> > > www.gridgain.com
> > >
> >
>
>
>
> --
> Andrey Gura
> GridGain Systems, Inc.
> www.gridgain.com
>
