Thank you guys so much for your explanations. I am now more clear with the IN_MEMORY setting. I will also try to use the APIs mentioned by Doug.
Thanks, ww On Fri, Jul 8, 2011 at 7:14 PM, Doug Meil <[email protected]>wrote: > > Weiwei, in addition to what Andy said you have control over what is used > in the block cache in your queries. See <Get>.setCacheBlocks and > <Scan>.setCacheBlocks. These are true by default. > > > > Thanks Andy for the explanation, the Hbase book doesn¹t explain this > enough. I'll submit a patch. > > > > > > > On 7/8/11 9:40 PM, "Andrew Purtell" <[email protected]> wrote: > > >IN_MEMORY means that HBase will try really hard to keep all of the data > >blocks for a table in the block cache. Block cache is expired on a LRU > >basis in three priority bands. Blocks for IN_MEMORY tables have the > >highest priority. They will be the last to be evicted. > > > >It does not mean data is never written to disk -- all data in HBase is > >backed by files in HDFS. > > > >It does not mean the table data won't be evicted if the table becomes > >very large and it cannot all fit in the available configured block cache. > > > >Best regards, > > > > > > - Andy > > > >Problems worthy of attack prove their worth by hitting back. - Piet Hein > >(via Tom White) > > > > > >----- Original Message ----- > >> From: Weiwei Xiong <[email protected]> > >> To: [email protected] > >> Cc: > >> Sent: Friday, July 8, 2011 6:04 PM > >> Subject: IN_MEMORY setting > >> > >> Hi all, > >> > >> Is there anyway to always keep a table in memory? Will IN_MEMORY setting > >> server this purpose? > >> > >> Thanks, > >> ww > >> > >
