Not really, only storing 1 value per column family is a fairly degenerate case and not really the primary mechanism by which people use hbase. The column family storage model may superficially appear to be like a column-store, but it can do so much more and is much more flexible.
On Fri, Jul 31, 2009 at 1:20 AM, Angus He<[email protected]> wrote: >> If you stored only 1 column per family, it would resemble a >> column-store, however as you stored more columns per family, they >> would be stored in "row order", ie: columns from the same row are >> stored next to each other. > > I know. And In previous post, I have mentioned "You cannot equate the > "column" in that article of wikipedia to the > "column" in HBase. > So we should consider the "column" in wikipedia as "column-family" in > HBase". > > Anyway, > Ryan, do you agree that hbase is a "column-family oriented db system"? > > > > >> >> On Fri, Jul 31, 2009 at 1:05 AM, Angus He<[email protected]> wrote: >>> OK,OK,OK. >>> >>> If data is stored row-by-row in hbase, how could you explain the text >>> under section "Physical Storage View" in >>> http://wiki.apache.org/hadoop/Hbase/HbaseArchitecture. >>> Is the page stale or something else wrong? >>> >>> On Fri, Jul 31, 2009 at 3:50 PM, Ryan Rawson<[email protected]> wrote: >>>> 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 >>>>> >>>> >>> >>> >>> >>> -- >>> Regards >>> Angus >>> >> > > > > -- > Regards > Angus >
