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HBase, mail # user - Adding String offset for ColumnPaginationFilter


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Adding String offset for ColumnPaginationFilter
Varun Sharma 2013-04-04, 17:31
Hi,

I am thinking of adding a string offset to ColumnPaginationFilter. There
are two reasons:

1) For deep pagination, you can seek using SEEK_NEXT_USING_HINT.
2) For correctness reasons, this approach is better if the list of columns
is mutation. Lets say you get 1st 50 columns using the current approach. In
the mean time some columns are inserted amongst the 1st 50 columns. Now you
request the 2nd set of 50 columns. Chances are that you will have
duplicates amongst the 2 sets (1st 50 and 2nd 50). If instead you used the
last column of the 1st 50 as a string offset for getting the 2nd set of
columns, the chances of getting dups is significantly lower.

This becomes important for user facing interactive applications.
Particularly where consistency etc. are not as important since those are
best effort services. But showing duplicates across pages is pretty bad.

Please let me know if this makes sense and is feasible. Basically, I would
like a string offset passed to ColumnPaginationFilter as an alternative
constructor. If the string offset is supplied, then, I would like to seek
to either the column supplied or if the column is deleted, seek to the
column just greater than the supplied column.

Thanks
Varun