Compression is at the block level within the StoreFile (Hfile), so yes, they can take advantage of compression.
On 1/21/12 12:49 PM, "Praveen Sripati" <[email protected]> wrote: >Thanks for the response. > >> The contents of a row stay together like a regular row-oriented >>database. > >> K: row-550/colfam1:50/1309813948188/Put/vlen=2 V: 50 >> K: row-550/colfam1:50/1309812287166/Put/vlen=2 V: 50 >> K: row-551/colfam1:51/1309813948222/Put/vlen=2 V: 51 >> K: row-551/colfam1:51/1309812287200/Put/vlen=2 V: 51 >> K: row-552/colfam1:52/1309813948256/Put/vlen=2 V: 52 > >Is the above statement true for a HFile? > >Also from the above example, the data for the column family qualifier are >not adjacent to take advantage of compression ( >http://en.wikipedia.org/wiki/Column-oriented_DBMS#Compression). Is this a >proper statement? > >Regards, >Praveen > >On Sat, Jan 21, 2012 at 9:03 PM, <[email protected]> wrote: > >> Have you considered using AggregationProtocol to perform aggregation ? >> >> Thanks >> >> >> >> On Jan 20, 2012, at 11:08 PM, Praveen Sripati <[email protected]> >> wrote: >> >> > Hi, >> > >> > 1) According to the this url (1), HBase performs well for two or three >> > column families. Why is it so? >> > >> > 2) Dump of a HFile, looks like below. The contents of a row stay >>together >> > like a regular row-oriented database. If the column family has 100 >>column >> > family qualifiers and is dense then the data for a particular column >> family >> > qualifier is spread wide. If I want to do an aggregation on a >>particular >> > column identifier, the disk seeks doesn't seems to be much better >>than a >> > regular row-oriented database. >> > >> > Please correct me if I am wrong. >> > >> > K: row-550/colfam1:50/1309813948188/Put/vlen=2 V: 50 >> > K: row-550/colfam1:50/1309812287166/Put/vlen=2 V: 50 >> > K: row-551/colfam1:51/1309813948222/Put/vlen=2 V: 51 >> > K: row-551/colfam1:51/1309812287200/Put/vlen=2 V: 51 >> > K: row-552/colfam1:52/1309813948256/Put/vlen=2 V: 52 >> > >> > (1) - http://hbase.apache.org/book/number.of.cfs.html >> > >> > Thanks, >> > Praveen >>
