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I am working with TIGER FILES, attempting to use the update (analysis) operation in ArcMap 10.1. The files I'm using are counties, and the incorporated (non-CDP) segment of the places file.

I'm using the counties as the input feature and the places as the update feature. My goal is a layer that has incorporated places, and the remaining (unincorporated) portions of counties.

Given that goal, is the update operation the right approach?

When I do use the update operation, I lose a bunch of the fields from the update features; union gives a more complete result from the perspective of field preservation, but non-contiguous segments of features are not preserved intact.

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You have posed two Questions and should probably consider splitting the second one out. In answer to the first one, I would use Union/Intersect/Identity (shich depends on the extent of output you want) rather than Update. – PolyGeo Apr 9 '13 at 5:20
@PolyGeo Thanks for the feedback. I did remove the second one. Would love to hear more about union/intersect/identity. In particular, advantages over update? Thanks! – dubhousing Apr 9 '13 at 14:58
Advantage is that they keep attributes of both/all inputs rather than just those of one. Try a simple test using Union and I think you will see the advantage straight away. – PolyGeo Apr 9 '13 at 21:12

Appreciate the feedback from @PolyGeo. I ended up using the update approach, but writing fields to the input features with the same name and type as those that resided only in the update features, in order to preserve those fields.

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