> On 2010-06-10 08:53:41, Jonathan Gray wrote: > > src/main/java/org/apache/hadoop/hbase/client/HTable.java, line 1079 > > <http://review.hbase.org/r/98/diff/5/?file=943#file943line1079> > > > > I guess these are static because of how HTables all share a single HCM > > per conf. The setting of prefetching is set at the HCM level not the > > HTable level, however clients are usually not exposed to HCM and only deal > > with HTable. > > > > We should probably make it clear in the javadoc for these methods that > > they apply to all HTable instances, though that may be clear from being > > static. > > > > Maybe since these are more advanced calls, they shouldn't be in HTable? > > If we provide proper documentation, it should be easy enough for a user to > > grab the HCM and apply the config at that level? > > Mingjie Lai wrote: > > I guess these are static because of how HTables all share a single HCM > per conf... > Yes. > > > Maybe since these are more advanced calls, they shouldn't be in HTable? > Two alternatives: > 1) HCM: as jgray said, ``however clients are usually not exposed to HCM > and only deal with HTable.'' > 2) HBaseAdmin: it is a more reasonable design choice since these > operation are at HCM level. > 3) or, make it a configuration. It would be one global configuration > applied to all tables, and cannot be changed dynamically. > > I like 2) better, but not really sure whether we want to expose it there > or not. > > What do you think?
Adding it to HBaseAdmin could make sense. This one is a bit of an odd one because it's a client-side configuration parameter done at the per-client-jvm level. Typically we have per-query or per-htable-instance configs. HBaseAdmin is generally made up of remote administration commands not local client config. If we provide sufficient javadoc (including as a class comment on HTable) it doesn't matter so much where we put it. Since it's distinct from what's currently in HTable and HBaseAdmin, maybe it does make sense as a static in HCM? - Jonathan ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: http://review.hbase.org/r/98/#review176 ----------------------------------------------------------- On 2010-06-09 15:50:59, Mingjie Lai wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > http://review.hbase.org/r/98/ > ----------------------------------------------------------- > > (Updated 2010-06-09 15:50:59) > > > Review request for hbase, Todd Lipcon and stack. > > > Summary > ------- > > HBASE-2468: Improvements to prewarm META cache on clients. > > Changes: > 1. Add new HTable methods which support region info de/serialation, and > region cache prewarm: > - void serializeRegionInfo(): clients could perform a large scan for all the > meta for the table, serialize the meta to a file. MR job can ship a copy of > the meta for the table in the DistributedCache > - Map<HRegionInfo, HServerAddress> deserializeRegionInfo(): MR job can > deserialize the region info from the DistributedCache > - prewarmRegionCache(Map<HRegionInfo, HServerAddress> regionMap): MR job can > prewarm local region cache by the deserialized region info. > > 2. For each client, each region cache read-miss could trigger read-ahead some > number of rows in META. This option could be turned on and off for one > particular table. > > > This addresses bug HBASE-2468. > http://issues.apache.org/jira/browse/HBASE-2468 > > > Diffs > ----- > > src/main/java/org/apache/hadoop/hbase/client/HConnection.java 853164d > src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java > ed18092 > src/main/java/org/apache/hadoop/hbase/client/HTable.java 7ec95cb > src/main/java/org/apache/hadoop/hbase/client/MetaScanner.java d3a0c07 > src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java > 95e494a > > Diff: http://review.hbase.org/r/98/diff > > > Testing > ------- > > Unit tests passed locally for me. > > > Thanks, > > Mingjie > >
