I currently have scf[c1][sc1]=value scf[c1][sc2]=value ... scf[c2][sc1]=value scf[c2][sc2]=value scf[c2][sc3]=value scf[c2][sc4]=value
99% of the time, I do multiget super slices: for multiple keys, I query for columns explicitly c1,c2,c10,c12 1% of the time, I do a multigetrange superslice where for multiple keys, I query for a range of super columns As Tyler said, it can be done by specifying supercolumns in the slice predicate, it will implicitly return all its columns. I use Hector and it works great. Now interestingly enough, column names sc1, sc2, sc3 are in fact home-made composite columns. I could and would switch to full composite columns because I am fishing for every drop of performance I can. However, I would need "Letting multiget_slice accept multiple SlicePredicates per key could also accomplish this." Can anyone on the dev team comment on doing this ? Is it a no-no ? Thanks 2011/12/29 Edward Capriolo <edlinuxg...@gmail.com> > Hum... > > Do you have this? > scf [b][1][a]=value > scf [b][1][x]=value > scf [b][7][b]=value > > and you want to slice: > scf [b][1][*] > > Which would result in > > scf [b][1][a]=value > scf [b][1][x]=value > > ? > > The composite version of this would be: > cf [b][1:a]=value > cf [b][1:x]=value > cf [b][7:b]=value > > I am not sure exactly what you are doing because A SlicePredicate > takes either a list of columns or a SliceRange. A ColumnPath takes a > Single SuperColumn. > > I do not see how this is done with Columns or SuperColumns. Maybe you > can provide a code snippet and/or some sample data? > > On 12/29/11, Aditya <ady...@gmail.com> wrote: > > @Edward: Perhaps you missed to notice that I need to always retrieve 'all > > columns' under the supercolumn at any time.. and as per my query > > requirements if I use composite columns instead of supercolumns then it > is > > impossible to do wildcard queries like the ones asked in this thread's > > headline but which is much easier to do through the use of supercolumns. > > > > On Thu, Dec 29, 2011 at 11:06 PM, Edward Capriolo > > <edlinuxg...@gmail.com>wrote: > > > >> The use case in question was: Only accessing some columns. > >> > >> Even if that is not the case: > >> > >> SuperColumns: 1 extra level of nesting > >> Composite Colunns: Arbitrary levels of nesting > >> > >> SuperColumns: More overhead (space on disk) then using your own > delimiter > >> '_' > >> SuperColumns: Likely going to be replaced in future c* version behind > >> the scenes by composite columns anyway > >> SuperColumns: Usually an afterthought for API developers, (support for > >> them comes "later") > >> SuperColumns: Almost always utilized incorrectly by users, users speak > >> of '10%' performance gains after they switch away from them. > >> > >> There are some (a small % of cases) where SuperColumns are a better > >> choice, but this is rare. With composites and concatenating columns > >> they have no great purpose any more, (bad analogy coming!) like a > >> mechanical type writer. > >> > >> On 12/29/11, Philippe <watche...@gmail.com> wrote: > >> > Would you stand by that statement in case all colums inside the super > >> > column need to be read? Why? > >> > > >> > Thanks > >> > Le 28 déc. 2011 19:26, "Edward Capriolo" <edlinuxg...@gmail.com> a > >> écrit : > >> > > >> >> Super columns have the same fundamental problem and perform worse in > >> >> general. So switching from composites to super columns is NEVER a > good > >> >> idea. > >> >> > >> >> > >> >> On Wed, Dec 28, 2011 at 1:19 PM, Aditya <ady...@gmail.com> wrote: > >> >> > >> >>> Since I have around 20 items to query, I guess making 20 queries to > >> >>> retrieve activities by all followies on all of those 20 columns > would > >> too > >> >>> inefficient, so to take the advantage of more efficient queries, are > >> >>> supercolumns recommended for this case ? Anyways, in case I use > >> >>> supercolumns, I need to retrieve the entire supercolumn at any point > >> >>> of > >> >>> time & I am writing subcolumn(s) to the supercolumn at different > times > >> >>> not > >> >>> at once. > >> >>> > >> >>> On Wed, Dec 28, 2011 at 8:07 PM, Edward Capriolo > >> >>> <edlinuxg...@gmail.com>wrote: > >> >>> > >> >>>> You need to execute one get slice operation for each item id or if > >> >>>> the > >> >>>> row is not large , you can try one large get slice on the entire > row > >> and > >> >>>> deal with the results client side. > >> >>>> > >> >>>> If you try method 1 When doing slices on composites you can set the > >> >>>> start inclusive or exclusive values to get only the column you want > >> and > >> >>>> not > >> >>>> some extra columns up to slice range size. > >> >>>> > >> >>>> > >> >>>> On Tuesday, December 27, 2011, Aditya <ady...@gmail.com> wrote: > >> >>>> > I need to store data of all activities by user's followies in > >> >>>> > single > >> >>>> row. I am trying to do that making use of composite column names > in a > >> >>>> single user specific row named 'rowX'. > >> >>>> > On any activity by a user's followie on an item, a column is > stored > >> in > >> >>>> 'rowX'. The column has a composite type column name made up of > >> >>>> itemId+userId (which makes it unique col. name) in rowX. (& column > >> value > >> >>>> contains the activity data related to that item by that followie) > >> >>>> > > >> >>>> > Now I want to retrieve activity by all users on a list of items. > So > >> I > >> >>>> need to retrieve all composite columns with composite's first > >> component > >> >>>> matching the itemId. Is it possible to do such a query to > Cassandra ? > >> I > >> >>>> am > >> >>>> using Hector. > >> >>>> > >> >>> > >> >>> > >> >> > >> > > >> > > >
