Hi, the open-source Java GQL parser (based on ANTLR) you can found here: http://code.google.com/p/audao/wiki/ExtendedGQLParser
Vaclav On Nov 24, 7:46 pm, Nacho Coloma <[email protected]> wrote: > > One other thought: instead of adding a GQL interpreter, you might just > > add a hook for loading a class provided by the user. That class would > > > implement a Filter interface with a method that takes a Configuration > > and returns a Query object so in your example, mailing and timestamp > > would get passed in as Configuration parameters and a query object > > corresponding to the GQL statement you put would be built by a Filter > > class provided by the user. It would act kind of like a templating > > language for building queries. Make sense/sound like a good idea? > > Actually, Filter would be simpler to implement and GQL can be added later as > a concrete Filter implementation if someone is still missing it (I doubt > it). It also solves the problem of specifying the type of arguments. > > BTW, arguments should be passed in as request parameters, not configuration > attributes (like "timestamp greater than" or "process all comments by user > X" for example). This means that Filter may need encapsulated access to some > methods of AppEngineJobContext.request. > > It seems that it can be implemented in a couple of hours. I will still wait > for 1.4.0, though. > > On Nov 18, 7:01 am, Nacho Coloma <[email protected]> wrote: > > > > > I'm not entirely sure I understand > > > > the scope of the proposed patch. Are you thinking about adding filters > > > > > at the DatastoreRecordReader level? It's not entirely clear to me that > > > > that provides a benefit over just applying the filter at the start of > > > > the map() function. Totally willing to believe I'm missing something, > > > > though. > > > > The map() filter runs against your quota. This is OK for once-only tasks > > > such as schema upgrades, but Mappers can also be used for repetitive > > tasks > > > such as mailing, data cleanup, etc. For these cases, being able to work > > on a > > > subset of data is important (process only user accounts with mailing > > > enabled, for example). > > > > The biggest problem to resolve is how to specify the filter clause in > > > mapreduce.xml. I am considering implementing a GQL parser as simple as > > > possible, and inject servlet request parameters. Something like: > > > > <property> > > > <name>mapreduce.mapper.inputformat.datastoreinputformat.query</name> > > > <value>select * from users where mailing=:value1 and > > > timestamp<=:value2</value> > > > </property> > > > > This implies porting the GQL implementation from python to Java, or > > > implementing an ANTLR-based parser. I feel like I am reinventing the > > wheel, > > > so any suggestion to use something that exists (or aim to a simpler > > design) > > > is welcome. > > > > On a logistical note, for nontrivial contributions, we require a CLA > > > > > from either you or your employer (depending on who owns the copyright > > > > for your work) before we can accept significant contributions. The > > > > relevant forms are at: > > > >http://code.google.com/legal/individual-cla-v1.0.html > > > > andhttp://code.google.com/legal/corporate-cla-v1.0.html. Feel free to > > > > email me privately if this is an issue. > > > > No problem with that. > > > > Regards, > > > > Nacho. > > > -- > > You received this message because you are subscribed to the Google Groups > > "Google App Engine for Java" group. > > To post to this group, send email to > > [email protected]. > > To unsubscribe from this group, send email to > > [email protected]<google-appengine-java%[email protected]> > > . > > For more options, visit this group at > >http://groups.google.com/group/google-appengine-java?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
