Sever, the IN_MEMORY option doesn't change when table content is transferred into RAM. Whether set to true or false, the blocks of data are only loaded into memory after a normal retrieval operation. When IN_MEMORY is set to true, HBase just tries to keep data in memory more aggressively than it normally would. This wiki explains it in more detail:
http://jimbojw.com/wiki/index.php?title=Understanding_HBase_column-family_performance_options ~ Minh On Wed, Jun 27, 2012 at 7:18 AM, Sever Fundatureanu <[email protected]> wrote: > Hello, > > I initially created a table without the IN_MEMORY option enabled and loaded > some data into it. Then I disabled it, modified the IN_MEMORY option using > the hbase shell 'alter' command, re-enabled it and finally ran a major > compaction. I do notice now the memory usage of the region servers has > increased. However for some queries I am still getting faster responses > only the 2nd time, as if I'm hitting the cache. Can someone tell me when > does the table content get transferred into RAM if IN_MEMORY option is > enabled like above? > > Thank you, > -- > Sever Fundatureanu > > Vrije Universiteit Amsterdam > E-mail: [email protected]
