If you do not bother about sequence number and the intention is to create just unique key, you can just use GUID which doesn't require any synchronization at all (all mappers can run in parallel).
The approached I suggested in earlier mail comes into picture mainly for sequence number. ~Rajesh.B On Sun, May 20, 2012 at 8:02 AM, Rajesh Balamohan < [email protected]> wrote: > Pig doesn't have that facility yet. Moreover, its not very efficient to do > this in PIG/MR as it requires synchronization. > > However, if this is unavoidable situation for you, following things can be > considered > > 1. Maintaining the seq number details in zookeeper > 2. Having a simple structure in HBase table (seqNumber --> Value). You can > get a bucket of values (ex: 1000-2000) from this and use it in your UDF. > When the range depletes, you have to query/update HBase table (ex: > 3000-4000). There are corner cases which needs to be handled. > > > ~Rajesh.B > > > On Sat, May 19, 2012 at 12:04 AM, DIPESH KUMAR SINGH < > [email protected]> wrote: > >> Sorry, if my point was not clear. >> >> I wish to create a sequence on a pig relation. >> >> Say For example i have a relation with data: >> (John, A-1) >> (Jack, B-2) >> (Jim, C-1) >> >> I want to create sequence i.e to add one more column to the relation, like >> a counter and keep on increasing the count for each record read. Expected >> output should be something like this: >> >> (If 200 is the start sequence. ) >> (John, A-1, 201) >> (Jack, B-2, 202) >> (Jim, C-1, 203) >> >> Could you please suggest to proceed on this? >> >> Thanks, >> Dipesh >> >> On Fri, May 18, 2012 at 6:50 AM, Thejas Nair <[email protected]> >> wrote: >> >> > What do you mean by 'rdbms like sequence' ? >> > Thanks, >> > Thejas >> > >> > >> > On 5/16/12 10:41 AM, DIPESH KUMAR SINGH wrote: >> > >> >> I want to create a rdbms like sequence on a Pig relation. >> >> >> >> Is there any existing UDF which could do this? >> >> >> >> I am bit new to pig, Kindly suggest how to proceed? >> >> >> >> >> >> Thanks& Regards, >> >> >> > >> > >> >> >> -- >> Dipesh Kr. Singh >> > > > > -- > ~Rajesh.B > -- ~Rajesh.B
