Hi Serkan, This is my personal opinion and some might not share it ;)
I tried to go with the deep versions approach for one project and I found issues on some of the calls (pagination over versions as an example). So if for you both (The deep version and wide columns) are the same, I will say, better go with the wide columns. Also, why not good with tall table instead of wide? JMS Le sam. 30 mars 2019 à 01:14, Serkan Uzunbaz <uzun...@gmail.com> a écrit : > Hi all, > I have a question regarding the difference between storing a set of data > as: > *a) n columns with 1 version each* > *b) 1 column with n versions* > > Since the storage unit in hbase is a cell (rowkey, column family, column > qualifier, timestamp), is there a difference between the above two storage > options in terms of read/write performance, compaction/GC time, etc? > > I know it is not recommended to use high number of versions if you do not > really need them. However, if those n versions of data are really needed > for reading, then will it cause any problem to store the data in a single > column with n versions. Also, even if max versions is set to 1 for a column > (option a), new values are still stored as a new cell and old cell is > deleted at compaction time. So, I also feel like compaction-wise two > options are identical. > I wonder if there is anything that makes one option superior to the other. > > *Example*: To clarify more, say the data to be stored is set of urls > visited in certain time ranges and we want to keep the last 100 hours of > url sets: > > *a) store each hour as column name with one url set in it (column names > will be used in cyclic manner (data for hour 101 will be written into > column 1))* > column_qualifier: value > --------------------------- > urls_hour1: <abc.com, xyz.com, ...> > urls_hour2: <urls> > urls_hour3: <urls> > ... > urls_hour100: <urls> > > > *b) store in a single column with 100 versions (one for each hour) (max > versions for column will be 100 and hbase will do the auto-compaction for > old versions)* > column_qualifier: value @ timestamp > --------------------------- > urls: <abc.com, xyz.com, ...> @ ts_hour1, <urls> @ ts_hour2, <urls> @ > ts_hour3, .... , <urls> @ ts_hour100 > > Thanks, > -Serkan >
