Wondering what other people think here ... And if we go for a documentation site that is "built" and released, how do we then bootstrap it easily with the knowledge that is currently in the wiki?
2014-03-25 20:35 GMT+01:00 Henry Saputra <[email protected]>: > Some projects do link back from homepage to wiki page. I think the > main key is to have separate docs for each release. > > What do you think? > > - Henry > > On Tue, Mar 25, 2014 at 4:47 AM, Kasper Sørensen > <[email protected]> wrote: > > Hmm was kinda hoping we wouldn't have to... But that's just because I am > > lazy and I prefer "live" (editable online) documentation where possible > > (that way you can easily react if someone starts pointing at missing > > parts). I think either way is doable, but you're right that in case we > use > > wiki-pages, each wiki page should clearly state which versions they apply > > to, if they are version-specific. > > > > > > 2014-03-24 23:03 GMT+01:00 Henry Saputra <[email protected]>: > > > >> Hmm seems like we need to bundle the doc for each release. For > >> example, the 4.0.0 does not have HBase store. > >> > >> Most projects have docs for each release on top of project homepage, > >> like Zookeeper http://zookeeper.apache.org/doc/r3.4.6/ or Spark > >> http://spark.apache.org/docs/0.9.0/ > >> > >> Thoughts? > >> > >> - Henry > >> > >> On Mon, Mar 24, 2014 at 2:50 PM, Kasper Sørensen > >> <[email protected]> wrote: > >> > Hmm I suppose a wiki page would be good. I guess we have wiki pages > for > >> > some of the DataContext implementations already like Salesforce [1], > POJO > >> > [2] and Composite [3] ... Maybe we should even have a page for *every > >> > *DataContext > >> > implementation there is, simply for completeness and referenceability > of > >> > documentation. > >> > > >> > [1] http://wiki.apache.org/metamodel/examples/SalesforceDataContext > >> > [2] http://wiki.apache.org/metamodel/examples/PojoDataContext > >> > [3] http://wiki.apache.org/metamodel/examples/CompositeDataContext > >> > > >> > > >> > 2014-03-24 22:44 GMT+01:00 Henry Saputra <[email protected]>: > >> > > >> >> Ok +1 > >> >> > >> >> How do you propose to document this feature? As another page in the > >> >> doc svn repo? > >> >> > >> >> - Henry > >> >> > >> >> On Mon, Mar 24, 2014 at 2:42 PM, Kasper Sørensen > >> >> <[email protected]> wrote: > >> >> > Yep. Or in slightly more technical terms: It means that the > >> >> > HBaseDataContext only implements DataContext which has these two > >> >> > significant methods: > >> >> > > >> >> > * getSchemas() > >> >> > * executeQuery(...) > >> >> > > >> >> > (Plus a bunch more methods, but those two give you the general > >> >> impression: > >> >> > Explore metadata and fire queries / reads) > >> >> > But not UpdateableDataContext, which has the write operations: > >> >> > > >> >> > * executeUpdate(...) > >> >> > > >> >> > Regards, > >> >> > Kasper > >> >> > > >> >> > > >> >> > 2014-03-24 22:37 GMT+01:00 Henry Saputra <[email protected] > >: > >> >> > > >> >> >> Hmm, what does it mean by read only? You can use it to read data > from > >> >> >> HBase? > >> >> >> > >> >> >> - Henry > >> >> >> > >> >> >> On Mon, Mar 24, 2014 at 2:34 PM, Kasper Sørensen > >> >> >> <[email protected]> wrote: > >> >> >> > A quick update on this since the module has now been merged into > >> the > >> >> >> master > >> >> >> > branch: > >> >> >> > > >> >> >> > 1) Module is still read-only. This is accepted for now (unless > >> someone > >> >> >> > wants to help change it of course). > >> >> >> > > >> >> >> > 2) Metadata mapping is still working in two modes: a) we > discover > >> the > >> >> >> > column families and expose them as byte-array maps (not very > >> useful, > >> >> but > >> >> >> > works as a "lowest common denominator") and b) the user > provides a > >> >> set of > >> >> >> > SimpleTableDef (which now has a convenient parser btw.:)) and > gets > >> his > >> >> >> > table mapping as he wants it. > >> >> >> > > >> >> >> > 3) Querying now has special support for lookup-by-id type > queries > >> >> where > >> >> >> we > >> >> >> > will use HBase Get instead of Scan. We also have good support > for > >> >> >> > LIMIT/"maxRows", but not OFFSET/"firstRow" (in those cases we > will > >> >> scan > >> >> >> > past the first records on the client side). > >> >> >> > > >> >> >> > 4) Dependencies seems to be a pain still. HBase and Hadoop > comes in > >> >> many > >> >> >> > flavours and all are not compatible. I doubt there's a lot we > can > >> do > >> >> >> about > >> >> >> > it, except ask the users to provide their own HBase dependency > as > >> per > >> >> >> their > >> >> >> > backend version. We should probably thus make all our > HBase/Hadoop > >> >> >> > dependencies <optional>true</optional> in order to not influence > >> the > >> >> >> > typical clients. > >> >> >> > > >> >> >> > Kasper > >> >> >> > > >> >> >> > > >> >> >> > 2014-02-24 17:08 GMT+01:00 Kasper Sørensen < > >> >> >> [email protected]>: > >> >> >> > > >> >> >> >> Hi Henry, > >> >> >> >> > >> >> >> >> Yea the Phoenix project is definately an interesting approach > to > >> >> making > >> >> >> MM > >> >> >> >> capable of working with HBase. The only downside to me is that > it > >> >> seems > >> >> >> >> they do a lot of intrusive stuff to HBase like creating new > index > >> >> tables > >> >> >> >> etc... I would normally not "allow" that for a simple > connector. > >> >> >> >> > >> >> >> >> Maybe we should simply support both styles. And in the case of > >> >> Phoenix, > >> >> >> I > >> >> >> >> guess we could simply go through the JDBC module of MetaModel > and > >> >> >> connect > >> >> >> >> via their JDBC driver... Is that maybe a route, do you know? > >> >> >> >> > >> >> >> >> - Kasper > >> >> >> >> > >> >> >> >> > >> >> >> >> 2014-02-24 6:37 GMT+01:00 Henry Saputra < > [email protected] > >> >: > >> >> >> >> > >> >> >> >> We could use the HBase client library from the store I suppose. > >> >> >> >>> The issue I am actually worry is actually adding real query > >> support > >> >> >> >>> for column based datastore is kind of big task. > >> >> >> >>> Apache Phoenix tried to do that so maybe we could leverage the > >> SQL > >> >> >> >>> planner layer to provide the implementation of the query > >> execution > >> >> to > >> >> >> >>> HBase layer? > >> >> >> >>> > >> >> >> >>> - Henry > >> >> >> >>> > >> >> >> >>> > >> >> >> >>> On Mon, Feb 17, 2014 at 9:33 AM, Kasper Sørensen > >> >> >> >>> <[email protected]> wrote: > >> >> >> >>> > Thanks for the input Henry. With your experience, do you > then > >> also > >> >> >> >>> happen > >> >> >> >>> > to know of a good thin client-side library? I imagine that > we > >> >> could > >> >> >> >>> maybe > >> >> >> >>> > use a REST client instead of the full client we currently > use. > >> >> That > >> >> >> >>> would > >> >> >> >>> > save us a ton of dependency-overhead I think. Or is it a > >> >> non-issue in > >> >> >> >>> your > >> >> >> >>> > mind, since HBase users are used to this overhead? > >> >> >> >>> > > >> >> >> >>> > > >> >> >> >>> > 2014-02-16 7:16 GMT+01:00 Henry Saputra < > >> [email protected] > >> >> >: > >> >> >> >>> > > >> >> >> >>> >> For 1 > I think adding read only to HBase should be ok > because > >> >> most > >> >> >> >>> >> update to HBase either through HBase client or REST via > >> Stargate > >> >> [1] > >> >> >> >>> >> or Thrift > >> >> >> >>> >> > >> >> >> >>> >> For 2 > In Apache Gora we use Avro to do type mapping to > >> column > >> >> and > >> >> >> >>> >> generate POJO java via Avro compiler. > >> >> >> >>> >> > >> >> >> >>> >> For 3 > This is the one I am kinda torn. Apache Phoenix > >> >> incubating > >> >> >> try > >> >> >> >>> >> to provide SQL to HBase [2] via extra indexing and > caching. I > >> >> think > >> >> >> >>> >> this is defeat the purpose of having NoSQL databases that > >> serve > >> >> >> >>> >> different purpose than Relational databse. > >> >> >> >>> >> > >> >> >> >>> >> I am not sure Metamodel should touch NoSQL databases which > >> more > >> >> like > >> >> >> >>> >> column types. These databases are designed for large data > with > >> >> >> access > >> >> >> >>> >> primary via key and not query mechanism. > >> >> >> >>> >> > >> >> >> >>> >> Just my 2-cent > >> >> >> >>> >> > >> >> >> >>> >> > >> >> >> >>> >> [1] http://wiki.apache.org/hadoop/Hbase/Stargate > >> >> >> >>> >> [2] http://phoenix.incubator.apache.org/ > >> >> >> >>> >> > >> >> >> >>> >> On Fri, Jan 24, 2014 at 11:35 AM, Kasper Sørensen > >> >> >> >>> >> <[email protected]> wrote: > >> >> >> >>> >> > Hi everyone, > >> >> >> >>> >> > > >> >> >> >>> >> > I was looking at our "hbase-module" branch and as much > as I > >> >> like > >> >> >> this > >> >> >> >>> >> idea, > >> >> >> >>> >> > I think we've been a bit too idle with the branch. Maybe > we > >> >> should > >> >> >> >>> try to > >> >> >> >>> >> > make something final e.g. for a version 4.1. > >> >> >> >>> >> > > >> >> >> >>> >> > So I thought to give an overview/status of the module's > >> current > >> >> >> >>> >> > capabilities and it's shortcomings. We should figure out > if > >> we > >> >> >> think > >> >> >> >>> this > >> >> >> >>> >> > is good enough for a first version, or if we want to do > some > >> >> >> >>> improvements > >> >> >> >>> >> > to the module before adding it to our portfolio of > MetaModel > >> >> >> modules. > >> >> >> >>> >> > > >> >> >> >>> >> > 1) The module only offers read-only/query access to > HBase. > >> >> That is > >> >> >> >>> in my > >> >> >> >>> >> > opinion OK for now, we have several such modules, and > this > >> is > >> >> >> >>> something > >> >> >> >>> >> we > >> >> >> >>> >> > can better add later if we straighten out the remaining > >> topics > >> >> in > >> >> >> >>> this > >> >> >> >>> >> mail. > >> >> >> >>> >> > > >> >> >> >>> >> > 2) With regards to metadata mapping: HBase is different > >> >> because it > >> >> >> >>> has > >> >> >> >>> >> both > >> >> >> >>> >> > column families and in column families there are columns. > >> For > >> >> the > >> >> >> >>> sake of > >> >> >> >>> >> > our view on HBase I would describe column families simply > >> as "a > >> >> >> >>> logical > >> >> >> >>> >> of > >> >> >> >>> >> > columns". Column families are fixed within a table, but > rows > >> >> in a > >> >> >> >>> table > >> >> >> >>> >> may > >> >> >> >>> >> > contain arbitrary numbers of columns within each column > >> family. > >> >> >> >>> So... You > >> >> >> >>> >> > can instantiate the HBaseDataContext in two ways: > >> >> >> >>> >> > > >> >> >> >>> >> > 2a) You can let MetaModel discover the metadata. This > >> >> >> unfortunately > >> >> >> >>> has a > >> >> >> >>> >> > severe limitation. We discover the table names and column > >> >> families > >> >> >> >>> using > >> >> >> >>> >> > the HBase API. But the actual columns and their contents > >> >> cannot be > >> >> >> >>> >> provided > >> >> >> >>> >> > by the API. So instead we simply expose the column > families > >> >> with a > >> >> >> >>> MAP > >> >> >> >>> >> data > >> >> >> >>> >> > types. The trouble with this is that the keys and values > of > >> the > >> >> >> maps > >> >> >> >>> will > >> >> >> >>> >> > simply be byte-arrays ... Usually not very useful! But > it's > >> >> sort > >> >> >> of > >> >> >> >>> the > >> >> >> >>> >> > only thing (as far as I can see) that's "safe" in HBase, > >> since > >> >> >> HBase > >> >> >> >>> >> allows > >> >> >> >>> >> > anything (byte arrays) in it's columns. > >> >> >> >>> >> > > >> >> >> >>> >> > 2b) Like in e.g. MongoDb or CouchDb modules you can > provide > >> an > >> >> >> array > >> >> >> >>> of > >> >> >> >>> >> > tables (SimpleTableDef). That way the user defines the > >> metadata > >> >> >> >>> himself > >> >> >> >>> >> and > >> >> >> >>> >> > the implementation assumes that it is correct (or else it > >> will > >> >> >> >>> break). > >> >> >> >>> >> The > >> >> >> >>> >> > good thing about this is that the user can define the > proper > >> >> data > >> >> >> >>> types > >> >> >> >>> >> > etc. for columns. The user defines the column family and > >> column > >> >> >> name > >> >> >> >>> by > >> >> >> >>> >> > setting defining the MetaModel column name as this: > >> >> "family:name" > >> >> >> >>> >> > (consistent with most HBase tools and API calls). > >> >> >> >>> >> > > >> >> >> >>> >> > 3) With regards to querying: We've implemented basic > query > >> >> >> >>> capabilities > >> >> >> >>> >> > using the MetaModel query postprocessor. But not all > queries > >> >> are > >> >> >> very > >> >> >> >>> >> > effective... In addition to of course full table scans, > we > >> have > >> >> >> >>> optimized > >> >> >> >>> >> > support of of COUNT queries and of table scans with > maxRows. > >> >> >> >>> >> > > >> >> >> >>> >> > We could rather easily add optimized support for a > couple of > >> >> other > >> >> >> >>> >> typical > >> >> >> >>> >> > queries: > >> >> >> >>> >> > * lookup record by ID > >> >> >> >>> >> > * paged table scans (both firstRow and maxRows) > >> >> >> >>> >> > * queries with simple filters/where items > >> >> >> >>> >> > > >> >> >> >>> >> > 4) With regards to dependencies: The module right now > >> depends > >> >> on > >> >> >> the > >> >> >> >>> >> > artifact called "hbase-client". This dependency has a > loot > >> of > >> >> >> >>> transient > >> >> >> >>> >> > dependencies so the size of the module is quite extreme. > As > >> an > >> >> >> >>> example, > >> >> >> >>> >> it > >> >> >> >>> >> > includes stuff like jetty, jersey, jackson and of course > >> >> hadoop... > >> >> >> >>> But I > >> >> >> >>> >> am > >> >> >> >>> >> > wondering if we can have a more thin client-side than > that! > >> If > >> >> >> anyone > >> >> >> >>> >> knows > >> >> >> >>> >> > if e.g. we can use the REST interface easily or so, that > >> would > >> >> >> maybe > >> >> >> >>> be > >> >> >> >>> >> > better. I'm not an expert on HBase though, so please > >> enlighten > >> >> me! > >> >> >> >>> >> > > >> >> >> >>> >> > Kind regards, > >> >> >> >>> >> > Kasper > >> >> >> >>> >> > >> >> >> >>> > >> >> >> >> > >> >> >> >> > >> >> >> > >> >> > >> >
