Data is stored row-by-row in the hbase store files (aka hfiles). HBase is not a column-oriented-store as described in the wikipedia article: http://en.wikipedia.org/wiki/Column-oriented_DBMS
Have a look at the bigtable paper, do some searches, lots of material out there describing the benefits of a flexible store like bigtable/hbase. -ryan On Fri, Jul 31, 2009 at 12:42 AM, Angus He<[email protected]> wrote: > Hi Ryan, > > You cannot equate the "column" in that article of wikipedia to the > "column" in HBase. > > We should assume that the word "column" in "column-oriented" is > predefined, otherwise, it is meaningless. > > So we should consider the "column" in wikipedia as "column-family" in > HBase. In this way, the article can answer 宏明's question. > > > On Fri, Jul 31, 2009 at 3:18 PM, Ryan Rawson<[email protected]> wrote: >> Hey, >> >> The bigtable paper talks more about column families, but in HBase each >> column family is stored in it's own file. That means there is disk >> locality for different column families. The canonical use is to put >> web crawl data in one family, and meta data (like derived meta data) >> in another. That way scanning just the meta data is not as expensive >> as scanning the web page crawl dump. >> >> Column families are pre-defined - the "schema" for what it's worth - >> but the 'qualifier' within a family is dynamically determined by the >> client. >> >> In the terminology of the article, hbase would be more 'row oriented', >> but with the column family snag, it isnt that simple. Since rows from >> different families are stored in different files, reading efficiency >> is related to which column families you are reading in a query. >> >> -ryan >> >> On Fri, Jul 31, 2009 at 12:02 AM, Angus He<[email protected]> wrote: >>> Hi Ryan, >>> >>> 1. If it is not the case , what is the purpose of introduction of >>> "column family"? >>> Does the contents from different column family stored in different >>> files in HBase? >>> >>> BTW, in the bigtable paper, we can find the following text: >>> "Access control and both disk and memory accounting are performed at >>> the column-family level." >>> >>> 2. I was wondering if HBase shares the benefits described in the >>> "Benefits" sections of wikipedia article. If not, what is the meaning >>> of "column-stores" in HBase? >>> >>> >>> >>> >>> >>> On Fri, Jul 31, 2009 at 2:30 PM, Ryan Rawson<[email protected]> wrote: >>>> HBase and bigtable are referred to column-stores, but we arent a >>>> 'column oriented dbms' as described in the wikipedia. >>>> >>>> At the storage level, hbase stores key-values, where the key is a >>>> triple of row / column / timestamp. Files are ordered lists of these >>>> key/values, and they are sorted in that order, hence rows are stored >>>> together, then sorted by column then reverse by timestamp (newest on >>>> top). >>>> >>>> Thus hbase is not a 'column store' in the sense listed in the wikipedia >>>> entry. >>>> >>>> On Thu, Jul 30, 2009 at 11:23 PM, Angus He<[email protected]> wrote: >>>>> Why don't you try to google it first? >>>>> After googling with the keyword "Column-oriented", the first result is >>>>> exactly what you want. >>>>> http://en.wikipedia.org/wiki/Column-oriented_DBMS >>>>> >>>>> >>>>> >>>>> 2009/7/31 <[email protected]>: >>>>>> Hi, >>>>>> Does anyone can tell me the benefit of Column-oriented data modal? >>>>>> Thank you >>>>>> >>>>>> Fleming >>>>>> 宏明 >>>>>> --------------------------------------------------------------------------- >>>>>> TSMC PROPERTY >>>>>> This email communication (and any attachments) is proprietary >>>>>> information >>>>>> for the sole use of its >>>>>> intended recipient. Any unauthorized review, use or distribution by >>>>>> anyone >>>>>> other than the intended >>>>>> recipient is strictly prohibited. If you are not the intended >>>>>> recipient, >>>>>> please notify the sender by >>>>>> replying to this email, and then delete this email and any copies of it >>>>>> immediately. Thank you. >>>>>> --------------------------------------------------------------------------- >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Regards >>>>> Angus >>>>> >>>> >>> >>> >>> >>> -- >>> Regards >>> Angus >>> >> > > > > -- > Regards > Angus >
