### Eclipse Workspace Patch 1.0 #P apache-trunk Index: src/docbkx/book.xml =================================================================== --- src/docbkx/book.xml (revision 1460946) +++ src/docbkx/book.xml (working copy) @@ -2175,6 +2175,28 @@ + +
+ Online Region Merges + + Both Master and Regionserver participate in the event of online region merges. + Client sends merge RPC to master, then master moves the regions together to the + same regionserver where the more heavily loaded region resided, finally master + send merge request to this regionserver and regionserver run the region merges. + Similar with process of region splits, region merges run as a local transaction + on the regionserver, offlines the regions and then merges two regions on the file + system, atomically delete merging regions from META and add merged region to the META, + opens merged region on the regionserver and reports the merge to Master at last. + + An example of region merges in the hbase shell + $ hbase> merge_region 'ENCODED_REGIONNAME', 'ENCODED_REGIONNAME' + hbase> merge_region 'ENCODED_REGIONNAME', 'ENCODED_REGIONNAME', true + + It's an asynchronous operation and call returns immediately without waiting merge completed. + Passing 'true' as the optional third parameter will force a merge ('force' merges regardless + else merge will fail unless passed adjacent regions. 'force' is for expert use only) + +
Store