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List:       drill-dev
Subject:    Re: contribution
From:       David Alves <davidralves () gmail ! com>
Date:       2013-03-15 21:36:14
Message-ID: D33571DB-CA64-46DA-A925-A003F5477CE4 () gmail ! com
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Hi Jacques

	Is there any chance we could get a preview of this physical plan stuff and basic \
plumbing for distributed execution before the weekend? maybe in a github branch \
somewhere?  I mean it doesn't have to be complete or even running, I'd just like to \
make some progress with other stuff and keeping it in line with whichever plumbing \
you already have would be great.  
Best
David

On Mar 13, 2013, at 3:12 PM, Jacques Nadeau <jacques@apache.org> wrote:

> I'm working on some physical plan stuff as well as some basic plumbing for
> distributed execution.  Its very in progress so I need to clean things up a
> bit before we could collaborate/ divide and conquer on it.  Depending on
> your timing and availability, maybe I could put some of this together in
> the next couple days so that you could plug in rather than reinvent.  In
> the meantime, pushing forward the builder stuff, additional test cases on
> the reference interpreter and/or thinking through the logical plan storage
> engine pushdown/rewrite could be very useful.
> 
> Let me know your thoughts.
> 
> thanks,
> Jacques
> 
> On Wed, Mar 13, 2013 at 9:47 AM, David Alves <davidralves@gmail.com> wrote:
> 
> > Hi Jacques
> > 
> > I can assign issues to me now, thanks.
> > What you say wrt to the logical/physical/execution layers sounds
> > good.
> > My main concern, for the moment is to have something working as
> > fast as possible, i.e. some daemons that I'd be able to deploy to a working
> > hbase cluster and send them work to do in some form (first step would be to
> > treat is as a non distributed engine where each daemon runs an instance of
> > the prototype).
> > Here's where I'd like to go next:
> > - lay the ground work for the daemons (scripts/rpc iface/wiring
> > protocol).
> > - create an execution engine iface that allows to abstract future
> > implementations, and make it available through the rpc iface. this would
> > sit in front of the ref impl for now and would be replaced by cpp down the
> > line.
> > 
> > I think we can probably concentrate on the capabilities iface a
> > bit down the line but, as a first approach, I see it simply providing a
> > simple set of ops that it is able to run internally.
> > How to abstract locality/partitioning/schema capabilities is till
> > not clear to me though, thoughts?
> > 
> > David
> > 
> > On Mar 13, 2013, at 11:12 AM, Jacques Nadeau <jacques@apache.org> wrote:
> > 
> > > I'm working on a presentation that will better illustrate the layers.
> > > There are actually three key plans.  Thinking to date has been to break
> > > the plans down into logical, physical and execution.  The third hasn't
> > been
> > > expressed well here and is entirely an internal domain to the execution
> > > engine.  Following some classic methods: Logical expresses what we want
> > to
> > > do, Physical expresses how we want to do it (adding points of
> > > parallelization but not specifying particular amounts of parallelization
> > or
> > > node by node assignments).  The execution engine is then responsible for
> > > determining the amount of parallelization of a particular plan along with
> > > system load (likely leveraging Berkeley's Sparrow work), task priority
> > and
> > > specific data locality information, building sub-dags to be assigned to
> > > individual nodes and execute the plan.
> > > 
> > > So in the higher logical and physical levels, a single Scan and
> > subsequent
> > > ScanPOP should be okay...  (ScanROPs have a separate problems since they
> > > ignore the level of separation we're planning for the real execution
> > layer.
> > > This is the why the current ref impl turns a single Scan into potentially
> > > a union of ScanROPs... not elegant but logically correct.)
> > > 
> > > The capabilities interface still needs to be defined for how a storage
> > > engine reveals its logical capabilities and thus consumes part of the
> > plan.
> > > 
> > > J
> > > 
> > > 
> > > On Tue, Mar 12, 2013 at 10:19 PM, David Alves <davidralves@gmail.com>
> > wrote:
> > > 
> > > > Hi Linsen
> > > > 
> > > > Some of what you are saying like push down of ops like filter,
> > > > projection or partial aggregation below the storage engine scanner
> > level,
> > > > or sub tree execution are actively being discussed in issues DRILL-13
> > > > (Strorage Engine Interface) and DRILL-15 (Hbase storage engine), your
> > input
> > > > in these issues is most welcome.
> > > > 
> > > > HBase in particular has the notion of
> > > > enpoints/coprocessors/filters that allow pushing this down easily (this
> > is
> > > > also in line with what other parallel database over nosql
> > implementations
> > > > like tajo do).
> > > > A possible approach is to have the optimizer change the order of
> > > > the ops to place them below the storage engine scanner and let the SE
> > impl
> > > > deal with it internally.
> > > > 
> > > > There are also some other pieces missing at the moment AFAIK,
> > like
> > > > a distributed metadata store, the drill daemons, wiring, etc.
> > > > 
> > > > So in summary, you're absolutely right, and if you're
> > particularly
> > > > interested in the HBase SE impl (as I am, for the moment) I'd be
> > interested
> > > > in collaborating.
> > > > 
> > > > Best
> > > > David
> > > > 
> > > > 
> > > > On Mar 12, 2013, at 11:44 PM, Lisen Mu <immars@gmail.com> wrote:
> > > > 
> > > > > Hi David,
> > > > > 
> > > > > Very nice to see your effort on this.
> > > > > 
> > > > > Hi Jacques,
> > > > > 
> > > > > we are also extending drill prototype, to see if there is any chance to
> > > > > meet our production need. However, We find that implementing a
> > performant
> > > > > HBase storage engine is a not so straight-forward work, and requires
> > some
> > > > > workaround. The problem is in Scan interface.
> > > > > 
> > > > > In drill's physical plan model, ScanROP is in charge of table scan.
> > > > Storage
> > > > > engine provides output for a whole data source, a csv file for example.
> > > > > It's sufficient for input source like plain file, but for hbase, it's
> > not
> > > > > very efficient, if not impossible, to let ScanROP retrieve a whole
> > htable
> > > > > into drill. Storage engines like HBase should have some ablility to do
> > > > part
> > > > > of the DrQL query, like Filter, if a filter can be performed by
> > > > specifying
> > > > > startRowKey and endRowKey. Storage engine like mysql could do more,
> > even
> > > > > Join.
> > > > > 
> > > > > Generally, it would be more clear if a ScanROP is mapped to a sub-DAG
> > of
> > > > > logical plan DAG instead of a single Scan node in logical plan. If so,
> > > > more
> > > > > implementation-specific information would coupe into the plan
> > > > optimization
> > > > > & transformation phase. I guess that's the price to pay when
> > optimization
> > > > > comes, or is there other way I failed to see?
> > > > > 
> > > > > Please correct me if anything is wrong.
> > > > > 
> > > > > thanks,
> > > > > 
> > > > > Lisen
> > > > > 
> > > > > 
> > > > > 
> > > > > On Wed, Mar 13, 2013 at 9:33 AM, David Alves <davidralves@gmail.com>
> > > > wrote:
> > > > > 
> > > > > > Hi Jacques
> > > > > > 
> > > > > > I've submitted a fist pass patch to DRILL-15.
> > > > > > I did this mostly because HBase will be my main target and
> > > > because
> > > > > > I wanted to get a feel of what would be a nice interface for DRILL-13.
> > > > Have
> > > > > > some thoughts that I will post soon.
> > > > > > btw: I still can't assign issues to myself in JIRA, did you
> > > > forget
> > > > > > to add me as a contributor?
> > > > > > 
> > > > > > Best
> > > > > > David
> > > > > > 
> > > > > > On Mar 11, 2013, at 2:13 PM, Jacques Nadeau <jacques@apache.org>
> > wrote:
> > > > > > 
> > > > > > > Hey David,
> > > > > > > 
> > > > > > > These sound good.  I've add you as a contributor on jira so you can
> > > > > > assign
> > > > > > > tasks to yourself.  I think 45 and 46 are good places to start.  15
> > > > > > depends
> > > > > > > on 13 and working on the two hand in hand would probably be a good
> > > > idea.
> > > > > > > Maybe we could do a design discussion on 15 and 13 here once you have
> > > > > > some
> > > > > > > time to focus on it.
> > > > > > > 
> > > > > > > Jacques
> > > > > > > 
> > > > > > > 
> > > > > > > On Mon, Mar 11, 2013 at 3:02 AM, David Alves <davidralves@gmail.com>
> > > > > > wrote:
> > > > > > > 
> > > > > > > > Hi All
> > > > > > > > 
> > > > > > > > I have a new academic project for which I'd like to use drill
> > > > > > > > since none of the other parallel database over hadoop/nosql
> > > > > > implementations
> > > > > > > > fit just right.
> > > > > > > > To this goal I've been tinkering with the prototype trying to
> > > > > > find
> > > > > > > > where I'd be most useful.
> > > > > > > > 
> > > > > > > > Here's where I'd like to start, if you agree:
> > > > > > > > - implement HBase storage engine (DRILL-15)
> > > > > > > > - start with simple scanning an push down of
> > > > > > > > selection/projection
> > > > > > > > - implement the LogicalPlanBuilder (DRILL-45)
> > > > > > > > - setup coding style in the wiki (formatting/imports etc,
> > > > > > DRILL-46)
> > > > > > > > - create builders for all logical plan elements/make logical
> > > > > > plans
> > > > > > > > immutable (no issue for this, I'd like to hear your thoughts first).
> > > > > > > > 
> > > > > > > > Please let me know your thoughts, and if you agree please
> > assign
> > > > > > > > the issues to me (it seems that I can't assign them myself).
> > > > > > > > 
> > > > > > > > Best
> > > > > > > > David Alves
> > > > > > 
> > > > > > 
> > > > 
> > > > 
> > 
> > 


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