Hi, I am steaming new on Accumulo, but tasked to put it into what used to be Apache Polygene (now in Attic) as a entity store, one that keeps history.
I have a couple of questions; 1. Assuming that I can guarantee that no one executes any explicit deletes, can I rely on the mutation sequences not disappearing over time? 2. Part of storing a row, I have a "metadata" qualifier, that contains static information. But since I don't know whether the row exists without reading it first, then IIUIC I will fill the "metadata" with the same information over and over again.... OR, does Accumulo realize that this is the same byte[] as before and won't update the value, alternatively creating a new Key, but pointing to the same Value? I effectively want a "putIfAbsent()" 3. The Scanner can fetch multiple rows, and constrained by CF and qualifier. I think that is quite clear. But what does the iterator() actually return? I presume that it is many key/value paris, of ALL timestamped values. But what is the order guarantees here? I get the impression that within a row->cf->qualifier, the returned values are in timestamp order, newest first. And I think that within a row, I am guaranteed that the order maintained, i.e. row -> cf -> qualifier (all ascending). But am I also guaranteed that the iterator is "done" with a row when the has changed? Or can rows be interleaved in the iterator? Thanks in advance Niclas
