BIND 10 #1330: Extend DatabaseAccessor to support reading diffs

[BIND 10 Development]

#1330: Extend DatabaseAccessor to support reading diffs
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                   Reporter:         |                 Owner:
  jinmei                             |                Status:  new
                       Type:  task   |             Milestone:  Next-Sprint-
                   Priority:  major  |  Proposed
                  Component:  data   |            Resolution:
  source                             |             Sensitive:  0
                   Keywords:         |           Sub-Project:  DNS
            Defect Severity:  N/A    |  Estimated Difficulty:  0
Feature Depending on Ticket:         |           Total Hours:  0
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Comment (by stephen):

 I think this needs a little more specification.  When it says "next "diff"
 in the form of RRset (in fact, essentially an "RR") ", is this:
 * One RR for every difference, with an indication of whether the RR was
 added or removed (so if an RR has been modified, it appears twice, once as
 the old version and once as the new)?
 * An iterator returning a pair of RRs, "first" holding the RR removed (so
 may be null) and "second" holding the one added (which also may be null).
 * Each RRset in the new version that has changed, with a special
 indication for where an RRset has been completely removed?
 * Two separate iterators, one for RRs that have been removed and one for
 the ones that have been added?
 * Does the list of RRs include the SOA record?

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Ticket URL: <http://bind10.isc.org/ticket/1330#comment:1>
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