In HBase API, there are classes defined on each level of structs. For example, HRegionInterface, HRegionInfo (HRegion), Store, StoreFile. I am not sure why there doesn't seem to have a clear way to traverse this hierarchical structure.
I can think of some downsides of using HDFS to get such information. 1. The user has to rebuild and maintain a similar hierarchy of struct classes on their end from the HDFS structure. For simple use case such as getting counts, it is probably OK but it could enforce the user to replicate the similar amount of work (which has been done on HBase API) for use cases that need more complicated meta information. 2. If a region is removed from meta store, there exists a timing between the time it is removed from meta store and that it is physically removed from HDFS. That said, it is not reliable. Chen On Tue, May 15, 2012 at 10:06 PM, Doug Meil <[email protected]>wrote: > > You're just doing a directory listing in HDFS to get this information. > That's a pretty lightweight operation (I.e., as opposed to transferring > the contents of all the StoreFiles, etc.) > > If you want to go all the way down to the StoreFile it's the only way I'm > aware of at this time. > > > > > On 5/15/12 5:37 PM, "Chen Song" <[email protected]> wrote: > > >Thanks Doug, that should work as the hierarchy is explicitly reflected on > >HDFS. But is this the preferred way to do such table/region/storefile > >traversal? > > > >I would like to avoid hitting to HDFS directly if possible as these pieces > >of meta information is within HBase world. > > > >Thanks > >Chen > > > >On Tue, May 15, 2012 at 5:23 PM, Doug Meil > ><[email protected]>wrote: > > > >> > >> You can get the Table->Region->StoreFile information via HDFS. That is > >> described here in the RefGuide: > >> > >> http://hbase.apache.org/book.html#trouble.namenode > >> > >> > >> > >> > >> > >> > >> On 5/15/12 5:09 PM, "Chen Song" <[email protected]> wrote: > >> > >> >I am new to HBase and started working on a project which needs meta > >> >information on HBase regions for a table. The version of HBase I am > >>using > >> >0.90.4. > >> > > >> >The use case is very simple. > >> > > >> >First, I want to get all regions for a table, which I can achieve using > >> >the > >> >API call below. > >> > > >> > HTable table = new HTable(conf, tableName); > >> > > >> > Map<HRegionInfo, HServerAddress> regions = table.getRegionsInfo(); > >> > > >> > > >> >Second, I want to get the list of stores (and then store files) for > >>each > >> >region. This is where I stuck as I could not find a way to do it by > >> >searching in the API. It seems that HRegionInterface started supporting > >> >API > >> >call to retrive the list of store files since 0.95-SNAPSHOT but I don't > >> >want to upgrade my HBase version. Below is how to get the corresponding > >> >HResionInterface. > >> > > >> > HConnection connection = table.getConnection(); > >> > > >> > HRegionInterface regionInterface = > >> >connection.getHRegionConnection(regionAddress); > >> > > >> >The series of objects I would like to get in sequence is like: > >>HRegionInfo > >> >-> HRegion -> Store/StoreFile/HFile. If some can help me with it, that > >> >would be great. > >> > > >> >Thanks very much, > >> > > >> >Chen > >> > >> > >> > > > > > >-- > >Chen Song > >Mobile: 518-445-5096 > > > -- Chen Song Mobile: 518-445-5096
