[fdo-internals] RE: MOTION: FDO RFC 34 - FDO Reader Access By Index

Wed Sep 16 12:52:51 EDT 2009

I agree with this.

FDO is already seen as large and awkward by much of the larger open source
community.  Anything that can be done to reduce complexity, or at least not
increase complexity, is good.

Jason

2009/9/16 Traian Stanev <traian.stanev at autodesk.com>

>
> Hi Dan,
>
> I think you are right, there are not many places where the performance gain
> would be significant -- but they do exist. Imagine a copy from one data
> source to another, of a feature class with 100K features and 100 columns --
> a common situation with street network files. For each feature, for each
> property,  you would have to do a name->index lookup inside the reader
> provider (SDF, SQLite, SHP or whatever other provider gets columns by index
> natively). Such lookups do get costly once you have lots of columns.
>
> If given a choice between the RFC34 as it is now and not having access by
> index at all, I would choose the latter -- i.e. I'd rather see the RFC
> withdrawn than implemented in a way that will require API users to write
> more code to use it than if they used access by name. Simply because if it's
> more work to use access by index, I don't see people switching their code
> around to make use of it.
>
> Traian
>
>
> > -----Original Message-----
> > From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Dan Stoica
> > Sent: Wednesday, September 16, 2009 9:54 AM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] RE: MOTION: FDO RFC 34 - FDO Reader Access By
> Index
> >
> > Talking about the performance gain it might be disappointing. The reason
> is
> > the access by name has been optimized for a number of providers.
> >
> > As for convenience, I'm not very sure either.
> >
> > Dan.
> >
> > -----Original Message-----
> > From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Klain Qin
> > Sent: Tuesday, September 15, 2009 10:02 PM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] RE: MOTION: FDO RFC 34 - FDO Reader Access By
> Index
> >
> > Yes, Carsten. You are right. This is exactly the way being proposed for
> the
> > default implementation as depicted in the RFC.
> >
> > Klain
> >
> > -----Original Message-----
> > From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Carsten Hess
> > Sent: Wednesday, September 16, 2009 9:39 AM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] RE: MOTION: FDO RFC 34 - FDO Reader Access By
> Index
> >
> > Hi,
> >
> > Couldn't the default implementation of the reader base class implement an
> > index based access using a name / index hashtable?
> > That way index based access would be about as slow as name based access
> in
> > the default cases and in providers taht override this index based
> behavior
> > the access would be faster. It also would not put a burden on the client
> > code while not loosing any performance in either case.
> >
> > Cheers,
> >    Carsten
> > ________________________________________
> > From: fdo-internals-bounces at lists.osgeo.org [fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Klain Qin [klain.qin at autodesk.com]
> > Sent: Tuesday, September 15, 2009 9:34 PM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] RE: MOTION: FDO RFC 34 - FDO Reader Access By
> Index
> >
> > To fix all of the providers internally would be hard and involve much
> work.
> > One example is: there are several providers like sqllite/rdbms which have
> > delay loading readers in some cases meaning the first property being
> > accessed will be first cached for class definition. There are other
> > complexities to ensure the consistency. So to provide an API like
> > GetPropertyIndex() would be easier for the users to use the new API
> > conveniently and correctly. The only concern is, as you mentioned, the
> > client codes have to keep a property name->index map by themselves. But
> > still providing this new API will be the easiest and least efforts at
> this
> > time.
> >
> > Klain
> >
> > From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Traian Stanev
> > Sent: Tuesday, September 15, 2009 10:25 PM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] RE: MOTION: FDO RFC 34 - FDO Reader Access By
> Index
> >
> >
> > How hard would it be to fix the providers internally so that the index of
> > the properties in the collection returned with GetClassDefinition
> > corresponds to the index needed for getting the property by index? I
> suspect
> > it is not too hard since it would involve the same amount of work as
> > implementing this new GetPropertyIndex API, but will not add new API that
> > one has to call before getting the properties by index.
> >
> >
> > Traian
> >
> >
> > From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Klain Qin
> > Sent: Monday, September 14, 2009 11:02 PM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] RE: MOTION: FDO RFC 34 - FDO Reader Access By
> Index
> >
> > Hi all,
> >
> > While this RFC is being voted, I've updated it again in order to use
> access
> > by index API more efficiently and correctly.
> >
> > Previously in order to use access by index functions for
> FdoIFeatureReader
> > or FdoIDataReader, the API users will have to know beforehand how index
> is
> > mapping to property name. And mapping is different for different provider
> > implementations like SqlLite/SDF and RDBMS. E.g. with the same FDO schema
> > definition, SqlLite and RDBMS will arrange the property order returned
> from
> > GetClassDefinition() differently:
> >
> >
> > a.       If you don't set selected property names be returned from an
> > FdoISelect command
> >
> >
> >
> > SqlLite provider will arrange the properties in the order: Identity
> property
> > -> Geometry property -> the left will be arranged in the order of how
> they
> > are added into the class definition, like ID -> geometry -> datetime->
> > double
> >
> > For RDBMS provider the order is: identity property -> the left is ordered
> by
> > the first character of the property name like ID -> datetime-> double ->
> > geometry
> >
> >
> >
> > b.      If you do set selected property names to be returned from an
> > FdoISelect command
> >
> >
> >
> > SqlLite provider will respect the order of how they are added to selected
> > properties.
> >
> > SDF provider will respect the order of corresponding properties defined
> in
> > the original class definition(without setting selected properties)
> >
> > So to resolve this inconvenience, RFC 34 is updated again to add another
> > function for getting the index of a specific property name. Now both of
> the
> > property name and index related functions are moved to FdoIReader as they
> > are needed for both FdoIFeatureReader and FdoIDataReader.
> > FdoString* GetPropertyName(FdoInt32 index);
> > FdoInt32 GetPropertyIndex(FdoString* propertyName);
> > Can you take a look again at this RFC?
> >
> > http://trac.osgeo.org/fdo/wiki/FDORfc34
> >
> > Thanks,
> > Klain
> >
> > From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Greg Boone
> > Sent: Monday, September 14, 2009 11:33 PM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] MOTION: FDO RFC 34 - FDO Reader Access By Index
> >
> > Hi all,
> >
> > There were no further comments on RFC 34:
> > http://trac.osgeo.org/fdo/wiki/FDORfc34  - FDO Reader Access By Index.
> >
> > I would like to motion a vote to accept this RFC.
> >
> > Thanks,
> > Greg.
> >
> >
> >
> > From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Greg Boone
> > Sent: Wednesday, September 09, 2009 12:41 PM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] RE: FDO RFC 34 - FDO Reader Access By Index
> >
> > Hi All,
> >
> > FDO RFC 34 - Access By Index: http://trac.osgeo.org/fdo/wiki/FDORfc34has
> > been updated and is ready for a secondary review.
> >
> > Please refer to the section labeled: "Provider Implementation"
> >
> > Please respond with comments by end of day, Friday September 11.
> >
> > Greg
> >
> > From: fdo-internals-bounces at lists.osgeo.org [mailto:fdo-internals-
> > bounces at lists.osgeo.org] On Behalf Of Greg Boone
> > Sent: Thursday, August 06, 2009 9:39 AM
> > To: FDO Internals Mail List
> > Subject: [fdo-internals] FDO RFC 34 - FDO Reader Access By Index
> >
> > Hi All,
> >
> > FDO RFC 34, http://trac.osgeo.org/fdo/wiki/FDORfc34, is ready for
> review.
> >
> > Please review and respond with comments.
> >
> > Greg
> >
> >
> >
> >
> > _______________________________________________
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