HBase has several subclasses of MapFile already: org.apache.hadoop.hbase.HStoreFile$ HbaseMapFile BloomFilterMapFile HalfMapFileReader
If MapFile were more subclassable (had protected members instead of private or accessor methods) we would probably add client side caching, bloom filters (to determine if a key exists in a map file - different from BloomFilterMapFile above which is a mix-in of MapFile and BloomFilter) Tom White said (in https://issues.apache.org/jira/browse/HADOOP-2604) > If MapFile.Reader were an interface (or an abstract class with a no > args constructor) then BloomFilterMapFile.Reader, HalfMapFileReader and > caching Readers could be implemented as wrappers instead of in a static > hierarchy. > > This would make it easier to mix and match readers (e.g. with or > without caching) without passing all possible parameters in the > constructor. So we'd like to make MapFile (and probably SequenceFile) subclassable by providing accessors and/or making members protected instead of private. If these classes should not be subclassed, they should be declared as final classes. Thoughts? Opinions? Comments? --- Jim Kellerman, Senior Engineer; Powerset No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.5/1228 - Release Date: 1/16/2008 9:01 AM
