A related question JG, do null column families take space? e.g, what if I create a column family which gets filles only in like 1 in a million rows and remains empty otherwise?
thanks, hari On Wed, Dec 22, 2010 at 7:14 AM, Jonathan Gray <[email protected]> wrote: > > > 1. It's a column based sparse table so null's take up no space(ie. > > More room when we need to duplicate) > > Correct. Nulls take up no space. > > > 2. Indexes take up space in an RDBMS already and are essentially > > duplication in your old RDBMS anyways > > Secondary indexes in an RDBMS use additional space. Primary indexes may > not depending on the db. > > > 3. The designs will be quite a bit different eliminating the need > > for those indexes(maybe we only have 3 later out of the 7, and the > indexes > > in hbase are a bit bigger than indexes in the old RDBMS too???) > > Designs will most likely be different. Number of indexes may not be the > same. Hard to say more without knowing the specifics. > > Hard to say what will be bigger where. HBase "indexes" (really just > tables) are generally highly compressible. This is generally not the case > for RDBMS indexes. > > An additional point about HBase vs. RDBMS when talking about disk space is > that HBase will work just fine on regular 7.2k RPM drives whereas good > performance from RDBMS indexes often require higher end 15k RPM drives (cost > per gigabyte is MUCH higher on these drives). > > > > > > > > > Thanks for any feedback here > > > > Dean > > > > > > This message and any attachments are intended only for the use of the > > addressee and may contain information that is privileged and > confidential. If > > the reader of the message is not the intended recipient or an authorized > > representative of the intended recipient, you are hereby notified that > any > > dissemination of this communication is strictly prohibited. If you have > > received this communication in error, please notify us immediately by > e-mail > > and delete the message and any attachments from your system. > >
