#806 Add _conflicts to the document in the map function

[pasin]

• When updating view index, gather a list of the conflict revisions if any.
• Add index conflict docs performance test to View_Benchmarks.
• Performance note when indexing 5000 documents, each has 0 conflict revisions (IP6 simulator):

SQLite:

Master branch:
[Time, seconds] average: 0.123, relative standard deviation: 4.698%, 
values: [0.137071, 0.118618, 0.122648, 0.118491, 0.119955, 0.130553, 0.125290, 0.121883, 0.118404, 0.120640]

_conflicts branch:
[Time, seconds] average: 0.127, relative standard deviation: 2.886%, 
values: [0.130026, 0.124279, 0.125534, 0.130044, 0.119877, 0.132092, 0.125637, 0.125442, 0.131264, 0.130175]

ForestDB:

Master branch:

[Time, seconds] average: 0.175, relative standard deviation: 0.806%, 
values: [0.173869, 0.176649, 0.173722, 0.175208, 0.176017, 0.172913, 0.175884, 0.172716, 0.174799, 0.176723]

_conflicts branch:
[Time, seconds] average: 0.172, relative standard deviation: 0.528%, 
values: [0.172850, 0.171485, 0.170446, 0.171153, 0.171059, 0.173832, 0.171988, 0.171561, 0.171765, 0.171921]

• Performance note when indexing 5000 documents, each has 100 conflict revisions (IP6 simulator):

SQLite:

Master branch:
[Time, seconds] average: 2.791, relative standard deviation: 0.972%, 
values: [2.838544, 2.784327, 2.784880, 2.747793, 2.820985, 2.789743, 2.765956, 2.775347, 2.824352, 2.774947],

_conflicts branch:
[Time, seconds] average: 3.039, relative standard deviation: 1.005%, 
values: [3.006172, 3.016779, 3.045371, 3.102432, 2.997188, 3.058586, 3.067990, 3.012772, 3.043481, 3.044008]

ForestDB:

Master branch:
[Time, seconds] average: 0.587, relative standard deviation: 0.885%, 
values: [0.580759, 0.590165, 0.585337, 0.583715, 0.588333, 0.588271, 0.585275, 0.585258, 0.583447, 0.600625], 

_conflicts branch:
[Time, seconds] average: 1.016, relative standard deviation: 8.155%, values: [1.261900, 0.983670, 0.984249, 0.984583, 0.984473, 0.980027, 0.984079, 1.019412, 0.988718, 0.984164]

** Update : Add Performance result for indexing 5000 docs without conflicts.
#806

[pasin]

With some possible perf cost, what do you think about overloading setMapBlock method with an option param (having a property to include _conflicts) to setMapBlock so by default the doc will not include _conficts?

[snej]

You can wrap this new code with if (vdoc.isConflicted()) { ... } to remove the overhead for docs without conflicts.

[snej]

I'm not worried about slowing down view indexing in the case where there are conflicts, since conflicts shouldn't be common. I'm just worried about slowing down indexing for the regular case where there are no conflicts. If you add the change I suggested above, there shouldn't be any noticeable overhead. Could you benchmark with and without your patch to look for a regression?

[pasin]

Yes, I will do that.

[pasin]

I made change as suggested. The change now doesn't affect non-conflicts indexing performance.