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:  stephen
  jinmei                             |                Status:  reviewing
                       Type:  task   |             Milestone:
                   Priority:  major  |  Sprint-20111122
                  Component:  data   |            Resolution:
  source                             |             Sensitive:  0
                   Keywords:         |           Sub-Project:  DNS
            Defect Severity:  N/A    |  Estimated Difficulty:  5
Feature Depending on Ticket:         |           Total Hours:  0
        Add Hours to Ticket:         |
                  Internal?:  0      |
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Comment (by jinmei):

 And yet another thing (this one is critical): aren't the OPERATION
 incorrect?
 0 = `DIFF_ADD` and 1 = `DIFF_DELETE`, so it seems to retrieve the first
 added record of the given begin serial to the last deleted record of the
 end serial (which is different from the IXFR ordering).
 {{{
     "SELECT id FROM diffs "     // LOW_DIFF_ID
         "WHERE zone_id=?1 AND version=?2 and OPERATION=0 "
         "ORDER BY id ASC LIMIT 1",
     "SELECT id FROM diffs "     // HIGH_DIFF_ID
         "WHERE zone_id=?1 AND version=?2 and OPERATION=1 "
         "ORDER BY id DESC LIMIT 1",
 }}}

 Also, we should probably document somewhere that in the SQLite3
 accessor we use consistent values for "operation" between the API
 and the database schema.

-- 
Ticket URL: <http://bind10.isc.org/ticket/1330#comment:15>
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