This can also be done with a row-doesn't-fit-into-memory constraint. You won't need to hold the second column in-memory if your iterator tree deep copies, filters, transforms and merges. Exhibit A:
[HeapIterator-derivative] |_________________________ | \ [transform-graph1-to-graph2] \ | \ [column-family-graph1] [all-but-column-family-graph1] With this design, you can subclass the HeapIterator, deep copy the source in the init method, wrap one in a custom transform iterator, and create a appropriate seek method. This is probably more on the advanced side of Accumulo programming, but can be done. Adam On Tue, May 26, 2015 at 8:59 AM, Eric Newton <eric.new...@gmail.com> wrote: > Short answer: no. > > Long answer: maybe. > > You can write an iterator which will transform: > > row, cf1, cq, vis -> value > > into: > > row, cf2, cq, vis -> value > > And if you can do this while maintaining sort order, you can get your new > ColumnFamily transformed during scans and compactions. > > But this bit about maintaining the sort order is more complex than it > sounds. > > If you have the following: > > row, a, cq, vis -> value > row, aa, cq, vis -> value > > > And you want to transform cf "a" into cf "b": > > row, aa, cq, vis -> value > row, b, cq, vis -> value > > > Your iterator needs to hold the second column in memory, after > transforming the first column. Tablet server memory for holding Key/Values > is not infinite. > > -Eric > > On Tue, May 26, 2015 at 8:44 AM, shweta.agrawal <shweta.agra...@orkash.com > > wrote: > >> Hi, >> >> I want to ask, is it possible in accumulo to change the column family >> without changing the whole data. >> >> Suppose my column family is graph1, now i want to rename this column >> family as graph2. >> Is it possible? >> >> Thanks >> Shweta >> > >
