Hi!
On Tue, Jun 2, 2009 at 11:17 AM, Guilherme Germoglio <[email protected]>wrote:
> Hi Erik,
>
> For now, I'm using checkAndSave in order to make sure that a row is only
> created but not overwritten by multiple threads. So, checkAndSave is mostly
> invoked with a new structure created on the client. Actually, I'm checking
> if a specific "deleted" column in empty. If the "deleted" column is not
> empty, then the row creation cannot be performed. There are another few
> tricky cases I'm using it, but I'm sure that making that Result object more
> difficult to create than putting values on a map would be bad for me. :-)
So you have a row with family and qualifier that you check to see if it is
empty
and if it is you insert a new row? So basically you use it as an atomic
rowExist
checker or? Are you usually batching this checks or would it be ok with
something like:
public boolean checkAndPut(byte[] row, byte[] family, byte[] qualifier,
byte[] value, Put put){}
or
public boolean checkAndPut(KeyValue checkKv, Put put){}
for now?
>
> However, here's an idea. What if Put and Delete objects have a field
> "condition" (maybe, "onlyIf" would be a better name) which is exactly the
> map with columns and expected values. So, a given Put or Delete of an
> updates list will only happen if those expected values match.
>
Puts and deletes are pretty much just List<KeyValue> which is basically a
List<byte[]>.
I don't think that we want to add complexity for puts and deletes now that
we have worked
so hard to make it faster and more bare bone.
> Also, maybe it should be possible to indicate common expected values for
> all
> updates of a list too, so a client won't have to put in all updates the
> same
> values if needed. But we must remember to solve the conflicts of expected
> values.
>
Not really sure if you mean that we would check the value of a key before
inserting the new
value? That would mean that you would have to do a get for every put/delete
which is not
something we want in the general case.
>
> (By the way, I haven't seen the guts of new Puts and Deletes, so I don't
> know how difficult would it be to implement it -- but I can help, if
> necessary)
>
> Thanks,
>
> On Tue, Jun 2, 2009 at 2:34 PM, Erik Holstad <[email protected]>
> wrote:
>
> > Hi!
> > I'm working on putting checkAndSave back into 0.20 and just want to check
> > with the people that are using it how they are using it
> > so that I can make it as good as possible for these users.
> >
> > Since the API has changed from earlier versions there are some things
> that
> > one need to think about.
> > For now in the new API there are now Updates, just Put and Delete, so for
> > now I need to know if users used to delete in the old batchUpdate
> > or just put?
> >
> > The new return format Result might seem like a good way to send in the
> data
> > to be used as "actual", but there is no super easy way to build that
> > on the client side for now, so would be good to know how you are doing
> > this.
> > If you do a get, save the result and then use it for the check or if you
> > just create new structures on the client?
> >
> > Regards Erik
> >
>
>
>
> --
> Guilherme
>
> msn: [email protected]
> homepage: http://germoglio.googlepages.com
>
Regards Erik
