You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@jena.apache.org by Diogo FC Patrao <dj...@gmail.com> on 2013/08/28 14:54:39 UTC
query planner
Hello
I was thinking about writing a query planner for federated queries. AFAIK,
there's no such thing on ARQ, and couldn't find any third-party libs for
that.
So my questions are:
1) do you know of any open source projects out there that deals with it?
I'm willing to contribute.
2) If there is no such project, is a Transformer the right place to go for
it? I thought about extending TransformerCopy to reorder OpJoins to solve
first those with smaller costs.
Thanks!
--
diogo patrão
Re: query planner
Posted by Diogo FC Patrao <dj...@gmail.com>.
Hi Claude
It is great insight you brought here indeed, thanks for sharing! Were the
endpoints triplestores? I'm using OBDA endpoints (like D2R), so performance
is definitely an issue to me.
In my case, endpoints contain complementary data, so when looking for all
instances of a class C I had to look at all endpoints e1..n, so I ended up
with n services with UNION, which is horribly slow and requires lots of
memory on the client.
The planner I was thinking of would benefit from some profiling of the
endpoints on time and number of instances each one contains. For instance,
when querying for instances of classes C1 AND C2 ( OpJoin( C1, C2 ) ) it is
faster to start by solving C1 or C2? it depends both on response time of
each endpoint and the number of results that each would yield.
Cheers!
--
diogo patrão
On Thu, Aug 29, 2013 at 10:47 AM, Claude Warren <cl...@xenei.com> wrote:
> The DERI work is supposed to be open source, however, I don't believe the
> papers have been written yet so I suspect they are not yet releasing the
> code.
>
> In my case we were building queries across multiple endpoints based upon
> the topics in an original query, so I was more concerned about writing a
> properly constructed federated query than about efficiency of the specific
> query. That being said, there were a couple of issues that we had to solve
> (most notably for optional values shared across the endpoints) to make the
> response time acceptable.
>
> In any case we simply passed the query transformed query to the default
> optimiser after we were done. The only optimisation that we did was to
> look at statements and run the ones with the fewest unknowns before queries
> with multiple unknowns. We probably could have added another layer of
> efficiency by placing statements with unknown predicates later in the
> query.
>
> We also did some work on response times from endpoints (we had cases where
> multiple SPARQL endpoints contained the same graphs so we had a choice of
> query points) and picking the most efficient for our query. We did the
> evaluation of responses on a schedule so we always had reasonably fresh
> data. This also allowed us to determine if an endpoint was down and switch
> to a backup or simply not generate the query for that endpoint.
>
> Hope this helps,
> Claude
>
>
> On Thu, Aug 29, 2013 at 1:52 PM, Diogo FC Patrao <djogopatrao@gmail.com
> >wrote:
>
> > Hi Claude
> >
> > Actually I did some testing with Transformer, which I'm more used to than
> > OpVisitor, and with it I can evaluate a cost function for each node.
> > However I would need several different trees to be evaluated in order to
> > find the best plan, and I can't see how Transformer could help on it.
> >
> > I was thinking that maybe ARQ has a default query planner that could be
> > substituted on configuration, or by applying a custom cost function.
> >
> > Was your work on DERI opensourced? Can you talk about it? I'm curious
> about
> > which strategies did you used on your planner.
> >
> > Cheers,
> >
> >
> >
> > --
> > diogo patrão
> >
> >
> >
> >
> > On Wed, Aug 28, 2013 at 6:24 PM, Claude Warren <cl...@xenei.com> wrote:
> >
> > > This discussion reminds me that a friend and I discussed the
> possibility
> > of
> > > adding pluggable OpVisitors to allow chained rewrites of the query
> before
> > > execution.
> > >
> > >
> > > On Wed, Aug 28, 2013 at 10:23 PM, Claude Warren <cl...@xenei.com>
> > wrote:
> > >
> > > > When I did the work on the query engine described above I used an
> > > > OpVisitor implementation in modifyOp to rewrite the query. It should
> > be
> > > > possible to implement the optimization there, but I don't know that
> it
> > is
> > > > the best place.
> > > >
> > > > Claude
> > > >
> > > >
> > > > On Wed, Aug 28, 2013 at 5:19 PM, Diogo FC Patrao <
> > djogopatrao@gmail.com
> > > >wrote:
> > > >
> > > >> Hi Claude
> > > >>
> > > >> I meant the first option, optimize queries to run at federated
> > > >> environments. Although I'm working on a query "federator" as well,
> and
> > > am
> > > >> also interested in similar projects as well.
> > > >>
> > > >> Thanks
> > > >>
> > > >> --
> > > >> diogo patrão
> > > >>
> > > >>
> > > >>
> > > >>
> > > >> On Wed, Aug 28, 2013 at 12:50 PM, Claude Warren <cl...@xenei.com>
> > > wrote:
> > > >>
> > > >> > I did some work on query planning for federated queries when I
> > worked
> > > >> for
> > > >> > DERI. (http://deri.ie). However, that work may have been a bit
> > more
> > > >> > complex than you are considering as we had some sources for
> > vocabulary
> > > >> > equivalence and were attempting to handle that at the same time.
> > > >> >
> > > >> > When you say a query planner for federated queries, are you
> looking
> > to
> > > >> > optimise queries that contain federated queries, or attempting to
> > > build
> > > >> a
> > > >> > federated query from a non-federated one?
> > > >> >
> > > >> > Claude
> > > >> >
> > > >> >
> > > >> > On Wed, Aug 28, 2013 at 1:54 PM, Diogo FC Patrao <
> > > djogopatrao@gmail.com
> > > >> > >wrote:
> > > >> >
> > > >> > > Hello
> > > >> > >
> > > >> > > I was thinking about writing a query planner for federated
> > queries.
> > > >> > AFAIK,
> > > >> > > there's no such thing on ARQ, and couldn't find any third-party
> > libs
> > > >> for
> > > >> > > that.
> > > >> > >
> > > >> > > So my questions are:
> > > >> > >
> > > >> > > 1) do you know of any open source projects out there that deals
> > with
> > > >> it?
> > > >> > > I'm willing to contribute.
> > > >> > >
> > > >> > > 2) If there is no such project, is a Transformer the right place
> > to
> > > go
> > > >> > for
> > > >> > > it? I thought about extending TransformerCopy to reorder OpJoins
> > to
> > > >> solve
> > > >> > > first those with smaller costs.
> > > >> > >
> > > >> > > Thanks!
> > > >> > >
> > > >> > >
> > > >> > > --
> > > >> > > diogo patrão
> > > >> > >
> > > >> >
> > > >> >
> > > >> >
> > > >> > --
> > > >> > I like: Like Like - The likeliest place on the web<
> > > >> > http://like-like.xenei.com>
> > > >> > Identity: https://www.identify.nu/user.php?claude@xenei.com
> > > >> > LinkedIn: http://www.linkedin.com/in/claudewarren
> > > >> >
> > > >>
> > > >
> > > >
> > > >
> > > > --
> > > > I like: Like Like - The likeliest place on the web<
> > > http://like-like.xenei.com>
> > > > Identity: https://www.identify.nu/user.php?claude@xenei.com
> > > > LinkedIn: http://www.linkedin.com/in/claudewarren
> > > >
> > >
> > >
> > >
> > > --
> > > I like: Like Like - The likeliest place on the web<
> > > http://like-like.xenei.com>
> > > Identity: https://www.identify.nu/user.php?claude@xenei.com
> > > LinkedIn: http://www.linkedin.com/in/claudewarren
> > >
> >
>
>
>
> --
> I like: Like Like - The likeliest place on the web<
> http://like-like.xenei.com>
> Identity: https://www.identify.nu/user.php?claude@xenei.com
> LinkedIn: http://www.linkedin.com/in/claudewarren
>
Re: query planner
Posted by Claude Warren <cl...@xenei.com>.
The DERI work is supposed to be open source, however, I don't believe the
papers have been written yet so I suspect they are not yet releasing the
code.
In my case we were building queries across multiple endpoints based upon
the topics in an original query, so I was more concerned about writing a
properly constructed federated query than about efficiency of the specific
query. That being said, there were a couple of issues that we had to solve
(most notably for optional values shared across the endpoints) to make the
response time acceptable.
In any case we simply passed the query transformed query to the default
optimiser after we were done. The only optimisation that we did was to
look at statements and run the ones with the fewest unknowns before queries
with multiple unknowns. We probably could have added another layer of
efficiency by placing statements with unknown predicates later in the
query.
We also did some work on response times from endpoints (we had cases where
multiple SPARQL endpoints contained the same graphs so we had a choice of
query points) and picking the most efficient for our query. We did the
evaluation of responses on a schedule so we always had reasonably fresh
data. This also allowed us to determine if an endpoint was down and switch
to a backup or simply not generate the query for that endpoint.
Hope this helps,
Claude
On Thu, Aug 29, 2013 at 1:52 PM, Diogo FC Patrao <dj...@gmail.com>wrote:
> Hi Claude
>
> Actually I did some testing with Transformer, which I'm more used to than
> OpVisitor, and with it I can evaluate a cost function for each node.
> However I would need several different trees to be evaluated in order to
> find the best plan, and I can't see how Transformer could help on it.
>
> I was thinking that maybe ARQ has a default query planner that could be
> substituted on configuration, or by applying a custom cost function.
>
> Was your work on DERI opensourced? Can you talk about it? I'm curious about
> which strategies did you used on your planner.
>
> Cheers,
>
>
>
> --
> diogo patrão
>
>
>
>
> On Wed, Aug 28, 2013 at 6:24 PM, Claude Warren <cl...@xenei.com> wrote:
>
> > This discussion reminds me that a friend and I discussed the possibility
> of
> > adding pluggable OpVisitors to allow chained rewrites of the query before
> > execution.
> >
> >
> > On Wed, Aug 28, 2013 at 10:23 PM, Claude Warren <cl...@xenei.com>
> wrote:
> >
> > > When I did the work on the query engine described above I used an
> > > OpVisitor implementation in modifyOp to rewrite the query. It should
> be
> > > possible to implement the optimization there, but I don't know that it
> is
> > > the best place.
> > >
> > > Claude
> > >
> > >
> > > On Wed, Aug 28, 2013 at 5:19 PM, Diogo FC Patrao <
> djogopatrao@gmail.com
> > >wrote:
> > >
> > >> Hi Claude
> > >>
> > >> I meant the first option, optimize queries to run at federated
> > >> environments. Although I'm working on a query "federator" as well, and
> > am
> > >> also interested in similar projects as well.
> > >>
> > >> Thanks
> > >>
> > >> --
> > >> diogo patrão
> > >>
> > >>
> > >>
> > >>
> > >> On Wed, Aug 28, 2013 at 12:50 PM, Claude Warren <cl...@xenei.com>
> > wrote:
> > >>
> > >> > I did some work on query planning for federated queries when I
> worked
> > >> for
> > >> > DERI. (http://deri.ie). However, that work may have been a bit
> more
> > >> > complex than you are considering as we had some sources for
> vocabulary
> > >> > equivalence and were attempting to handle that at the same time.
> > >> >
> > >> > When you say a query planner for federated queries, are you looking
> to
> > >> > optimise queries that contain federated queries, or attempting to
> > build
> > >> a
> > >> > federated query from a non-federated one?
> > >> >
> > >> > Claude
> > >> >
> > >> >
> > >> > On Wed, Aug 28, 2013 at 1:54 PM, Diogo FC Patrao <
> > djogopatrao@gmail.com
> > >> > >wrote:
> > >> >
> > >> > > Hello
> > >> > >
> > >> > > I was thinking about writing a query planner for federated
> queries.
> > >> > AFAIK,
> > >> > > there's no such thing on ARQ, and couldn't find any third-party
> libs
> > >> for
> > >> > > that.
> > >> > >
> > >> > > So my questions are:
> > >> > >
> > >> > > 1) do you know of any open source projects out there that deals
> with
> > >> it?
> > >> > > I'm willing to contribute.
> > >> > >
> > >> > > 2) If there is no such project, is a Transformer the right place
> to
> > go
> > >> > for
> > >> > > it? I thought about extending TransformerCopy to reorder OpJoins
> to
> > >> solve
> > >> > > first those with smaller costs.
> > >> > >
> > >> > > Thanks!
> > >> > >
> > >> > >
> > >> > > --
> > >> > > diogo patrão
> > >> > >
> > >> >
> > >> >
> > >> >
> > >> > --
> > >> > I like: Like Like - The likeliest place on the web<
> > >> > http://like-like.xenei.com>
> > >> > Identity: https://www.identify.nu/user.php?claude@xenei.com
> > >> > LinkedIn: http://www.linkedin.com/in/claudewarren
> > >> >
> > >>
> > >
> > >
> > >
> > > --
> > > I like: Like Like - The likeliest place on the web<
> > http://like-like.xenei.com>
> > > Identity: https://www.identify.nu/user.php?claude@xenei.com
> > > LinkedIn: http://www.linkedin.com/in/claudewarren
> > >
> >
> >
> >
> > --
> > I like: Like Like - The likeliest place on the web<
> > http://like-like.xenei.com>
> > Identity: https://www.identify.nu/user.php?claude@xenei.com
> > LinkedIn: http://www.linkedin.com/in/claudewarren
> >
>
--
I like: Like Like - The likeliest place on the web<http://like-like.xenei.com>
Identity: https://www.identify.nu/user.php?claude@xenei.com
LinkedIn: http://www.linkedin.com/in/claudewarren
Re: query planner
Posted by Diogo FC Patrao <dj...@gmail.com>.
Hi Claude
Actually I did some testing with Transformer, which I'm more used to than
OpVisitor, and with it I can evaluate a cost function for each node.
However I would need several different trees to be evaluated in order to
find the best plan, and I can't see how Transformer could help on it.
I was thinking that maybe ARQ has a default query planner that could be
substituted on configuration, or by applying a custom cost function.
Was your work on DERI opensourced? Can you talk about it? I'm curious about
which strategies did you used on your planner.
Cheers,
--
diogo patrão
On Wed, Aug 28, 2013 at 6:24 PM, Claude Warren <cl...@xenei.com> wrote:
> This discussion reminds me that a friend and I discussed the possibility of
> adding pluggable OpVisitors to allow chained rewrites of the query before
> execution.
>
>
> On Wed, Aug 28, 2013 at 10:23 PM, Claude Warren <cl...@xenei.com> wrote:
>
> > When I did the work on the query engine described above I used an
> > OpVisitor implementation in modifyOp to rewrite the query. It should be
> > possible to implement the optimization there, but I don't know that it is
> > the best place.
> >
> > Claude
> >
> >
> > On Wed, Aug 28, 2013 at 5:19 PM, Diogo FC Patrao <djogopatrao@gmail.com
> >wrote:
> >
> >> Hi Claude
> >>
> >> I meant the first option, optimize queries to run at federated
> >> environments. Although I'm working on a query "federator" as well, and
> am
> >> also interested in similar projects as well.
> >>
> >> Thanks
> >>
> >> --
> >> diogo patrão
> >>
> >>
> >>
> >>
> >> On Wed, Aug 28, 2013 at 12:50 PM, Claude Warren <cl...@xenei.com>
> wrote:
> >>
> >> > I did some work on query planning for federated queries when I worked
> >> for
> >> > DERI. (http://deri.ie). However, that work may have been a bit more
> >> > complex than you are considering as we had some sources for vocabulary
> >> > equivalence and were attempting to handle that at the same time.
> >> >
> >> > When you say a query planner for federated queries, are you looking to
> >> > optimise queries that contain federated queries, or attempting to
> build
> >> a
> >> > federated query from a non-federated one?
> >> >
> >> > Claude
> >> >
> >> >
> >> > On Wed, Aug 28, 2013 at 1:54 PM, Diogo FC Patrao <
> djogopatrao@gmail.com
> >> > >wrote:
> >> >
> >> > > Hello
> >> > >
> >> > > I was thinking about writing a query planner for federated queries.
> >> > AFAIK,
> >> > > there's no such thing on ARQ, and couldn't find any third-party libs
> >> for
> >> > > that.
> >> > >
> >> > > So my questions are:
> >> > >
> >> > > 1) do you know of any open source projects out there that deals with
> >> it?
> >> > > I'm willing to contribute.
> >> > >
> >> > > 2) If there is no such project, is a Transformer the right place to
> go
> >> > for
> >> > > it? I thought about extending TransformerCopy to reorder OpJoins to
> >> solve
> >> > > first those with smaller costs.
> >> > >
> >> > > Thanks!
> >> > >
> >> > >
> >> > > --
> >> > > diogo patrão
> >> > >
> >> >
> >> >
> >> >
> >> > --
> >> > I like: Like Like - The likeliest place on the web<
> >> > http://like-like.xenei.com>
> >> > Identity: https://www.identify.nu/user.php?claude@xenei.com
> >> > LinkedIn: http://www.linkedin.com/in/claudewarren
> >> >
> >>
> >
> >
> >
> > --
> > I like: Like Like - The likeliest place on the web<
> http://like-like.xenei.com>
> > Identity: https://www.identify.nu/user.php?claude@xenei.com
> > LinkedIn: http://www.linkedin.com/in/claudewarren
> >
>
>
>
> --
> I like: Like Like - The likeliest place on the web<
> http://like-like.xenei.com>
> Identity: https://www.identify.nu/user.php?claude@xenei.com
> LinkedIn: http://www.linkedin.com/in/claudewarren
>
Re: query planner
Posted by Claude Warren <cl...@xenei.com>.
This discussion reminds me that a friend and I discussed the possibility of
adding pluggable OpVisitors to allow chained rewrites of the query before
execution.
On Wed, Aug 28, 2013 at 10:23 PM, Claude Warren <cl...@xenei.com> wrote:
> When I did the work on the query engine described above I used an
> OpVisitor implementation in modifyOp to rewrite the query. It should be
> possible to implement the optimization there, but I don't know that it is
> the best place.
>
> Claude
>
>
> On Wed, Aug 28, 2013 at 5:19 PM, Diogo FC Patrao <dj...@gmail.com>wrote:
>
>> Hi Claude
>>
>> I meant the first option, optimize queries to run at federated
>> environments. Although I'm working on a query "federator" as well, and am
>> also interested in similar projects as well.
>>
>> Thanks
>>
>> --
>> diogo patrão
>>
>>
>>
>>
>> On Wed, Aug 28, 2013 at 12:50 PM, Claude Warren <cl...@xenei.com> wrote:
>>
>> > I did some work on query planning for federated queries when I worked
>> for
>> > DERI. (http://deri.ie). However, that work may have been a bit more
>> > complex than you are considering as we had some sources for vocabulary
>> > equivalence and were attempting to handle that at the same time.
>> >
>> > When you say a query planner for federated queries, are you looking to
>> > optimise queries that contain federated queries, or attempting to build
>> a
>> > federated query from a non-federated one?
>> >
>> > Claude
>> >
>> >
>> > On Wed, Aug 28, 2013 at 1:54 PM, Diogo FC Patrao <djogopatrao@gmail.com
>> > >wrote:
>> >
>> > > Hello
>> > >
>> > > I was thinking about writing a query planner for federated queries.
>> > AFAIK,
>> > > there's no such thing on ARQ, and couldn't find any third-party libs
>> for
>> > > that.
>> > >
>> > > So my questions are:
>> > >
>> > > 1) do you know of any open source projects out there that deals with
>> it?
>> > > I'm willing to contribute.
>> > >
>> > > 2) If there is no such project, is a Transformer the right place to go
>> > for
>> > > it? I thought about extending TransformerCopy to reorder OpJoins to
>> solve
>> > > first those with smaller costs.
>> > >
>> > > Thanks!
>> > >
>> > >
>> > > --
>> > > diogo patrão
>> > >
>> >
>> >
>> >
>> > --
>> > I like: Like Like - The likeliest place on the web<
>> > http://like-like.xenei.com>
>> > Identity: https://www.identify.nu/user.php?claude@xenei.com
>> > LinkedIn: http://www.linkedin.com/in/claudewarren
>> >
>>
>
>
>
> --
> I like: Like Like - The likeliest place on the web<http://like-like.xenei.com>
> Identity: https://www.identify.nu/user.php?claude@xenei.com
> LinkedIn: http://www.linkedin.com/in/claudewarren
>
--
I like: Like Like - The likeliest place on the web<http://like-like.xenei.com>
Identity: https://www.identify.nu/user.php?claude@xenei.com
LinkedIn: http://www.linkedin.com/in/claudewarren
Re: query planner
Posted by Claude Warren <cl...@xenei.com>.
When I did the work on the query engine described above I used an OpVisitor
implementation in modifyOp to rewrite the query. It should be possible to
implement the optimization there, but I don't know that it is the best
place.
Claude
On Wed, Aug 28, 2013 at 5:19 PM, Diogo FC Patrao <dj...@gmail.com>wrote:
> Hi Claude
>
> I meant the first option, optimize queries to run at federated
> environments. Although I'm working on a query "federator" as well, and am
> also interested in similar projects as well.
>
> Thanks
>
> --
> diogo patrão
>
>
>
>
> On Wed, Aug 28, 2013 at 12:50 PM, Claude Warren <cl...@xenei.com> wrote:
>
> > I did some work on query planning for federated queries when I worked for
> > DERI. (http://deri.ie). However, that work may have been a bit more
> > complex than you are considering as we had some sources for vocabulary
> > equivalence and were attempting to handle that at the same time.
> >
> > When you say a query planner for federated queries, are you looking to
> > optimise queries that contain federated queries, or attempting to build a
> > federated query from a non-federated one?
> >
> > Claude
> >
> >
> > On Wed, Aug 28, 2013 at 1:54 PM, Diogo FC Patrao <djogopatrao@gmail.com
> > >wrote:
> >
> > > Hello
> > >
> > > I was thinking about writing a query planner for federated queries.
> > AFAIK,
> > > there's no such thing on ARQ, and couldn't find any third-party libs
> for
> > > that.
> > >
> > > So my questions are:
> > >
> > > 1) do you know of any open source projects out there that deals with
> it?
> > > I'm willing to contribute.
> > >
> > > 2) If there is no such project, is a Transformer the right place to go
> > for
> > > it? I thought about extending TransformerCopy to reorder OpJoins to
> solve
> > > first those with smaller costs.
> > >
> > > Thanks!
> > >
> > >
> > > --
> > > diogo patrão
> > >
> >
> >
> >
> > --
> > I like: Like Like - The likeliest place on the web<
> > http://like-like.xenei.com>
> > Identity: https://www.identify.nu/user.php?claude@xenei.com
> > LinkedIn: http://www.linkedin.com/in/claudewarren
> >
>
--
I like: Like Like - The likeliest place on the web<http://like-like.xenei.com>
Identity: https://www.identify.nu/user.php?claude@xenei.com
LinkedIn: http://www.linkedin.com/in/claudewarren
Re: query planner
Posted by Diogo FC Patrao <dj...@gmail.com>.
Hi Claude
I meant the first option, optimize queries to run at federated
environments. Although I'm working on a query "federator" as well, and am
also interested in similar projects as well.
Thanks
--
diogo patrão
On Wed, Aug 28, 2013 at 12:50 PM, Claude Warren <cl...@xenei.com> wrote:
> I did some work on query planning for federated queries when I worked for
> DERI. (http://deri.ie). However, that work may have been a bit more
> complex than you are considering as we had some sources for vocabulary
> equivalence and were attempting to handle that at the same time.
>
> When you say a query planner for federated queries, are you looking to
> optimise queries that contain federated queries, or attempting to build a
> federated query from a non-federated one?
>
> Claude
>
>
> On Wed, Aug 28, 2013 at 1:54 PM, Diogo FC Patrao <djogopatrao@gmail.com
> >wrote:
>
> > Hello
> >
> > I was thinking about writing a query planner for federated queries.
> AFAIK,
> > there's no such thing on ARQ, and couldn't find any third-party libs for
> > that.
> >
> > So my questions are:
> >
> > 1) do you know of any open source projects out there that deals with it?
> > I'm willing to contribute.
> >
> > 2) If there is no such project, is a Transformer the right place to go
> for
> > it? I thought about extending TransformerCopy to reorder OpJoins to solve
> > first those with smaller costs.
> >
> > Thanks!
> >
> >
> > --
> > diogo patrão
> >
>
>
>
> --
> I like: Like Like - The likeliest place on the web<
> http://like-like.xenei.com>
> Identity: https://www.identify.nu/user.php?claude@xenei.com
> LinkedIn: http://www.linkedin.com/in/claudewarren
>
Re: query planner
Posted by Claude Warren <cl...@xenei.com>.
I did some work on query planning for federated queries when I worked for
DERI. (http://deri.ie). However, that work may have been a bit more
complex than you are considering as we had some sources for vocabulary
equivalence and were attempting to handle that at the same time.
When you say a query planner for federated queries, are you looking to
optimise queries that contain federated queries, or attempting to build a
federated query from a non-federated one?
Claude
On Wed, Aug 28, 2013 at 1:54 PM, Diogo FC Patrao <dj...@gmail.com>wrote:
> Hello
>
> I was thinking about writing a query planner for federated queries. AFAIK,
> there's no such thing on ARQ, and couldn't find any third-party libs for
> that.
>
> So my questions are:
>
> 1) do you know of any open source projects out there that deals with it?
> I'm willing to contribute.
>
> 2) If there is no such project, is a Transformer the right place to go for
> it? I thought about extending TransformerCopy to reorder OpJoins to solve
> first those with smaller costs.
>
> Thanks!
>
>
> --
> diogo patrão
>
--
I like: Like Like - The likeliest place on the web<http://like-like.xenei.com>
Identity: https://www.identify.nu/user.php?claude@xenei.com
LinkedIn: http://www.linkedin.com/in/claudewarren