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HBase, mail # user - checkAnd...


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Re: checkAnd...
Lior Schachter 2013-04-27, 13:45
Hi Ted,
Thanks for the prompt response.
I've already had a look at HRegionServer.checkAndPut and the implementation
looks quite straight forward.
That's why I was wondering why the other 2 methods are not available...or
planned (couldn't find Jira).
Seems like a useful functionality.

Anyhow, I'm not allowed to make any source code modifications to the HBase
installation (in production) so I reckon I'll have to find a workaround.

This is my use case:
Updating user counters by events.
We may get (in rare cases) duplicate events.
Should not count the duplicates.

My initial thought was to have an event_id qualifier for each incoming
event (with '1' value). By checking if event_id exists before incrementing
I can avoid duplicates.
Without the checkAndIncrement functionality I must make 2 round trips for
each event (which doesn't make sense).

Any ideas how I can solve this issue ?

Thanks,
Lior
On Sat, Apr 27, 2013 at 4:23 PM, Ted Yu <[EMAIL PROTECTED]> wrote:

> Take a look at the following method in HRegionServer:
>
>   public boolean checkAndPut(final byte[] regionName, final byte[] row,
>       final byte[] family, final byte[] qualifier, final byte[] value,
>       final Put put) throws IOException {
>
> You can create checkAndIncrement() in a similar way.
>
> Cheers
>
> On Sat, Apr 27, 2013 at 9:02 PM, Lior Schachter <[EMAIL PROTECTED]> wrote:
>
> > Hi,
> > I want to increment a cell value only after checking a condition on
> another
> > cell. I could find checkAndPut/checkAndDelete on HTableInteface. It seems
> > that checkAndIncrement (and checkAndAppend) are missing.
> >
> > Can you suggest a workaround for my use-case ?  working with version
> > 0.94.5.
> >
> > Thanks,
> > Lior
> >
>