What does the dedupe parameter do in the Nominatim search API?
It seems to do more than just remove duplicates, but I can't find any good documentation on it. The API docs currently just say:
DeDupe = [0 | 1]
No explanation yet.
I am running my own Nominatim which was forked from the original a few months ago and I use the Nominatim post as a backup when mine is not responding. Therefore, I am interested in the answers regarding the last public Nominatima. In my Nominatime, I did not notice duplicate results.
I noticed differences when setting dedupe
to 0
or 1
. Here's a diff where you can see that even with no dedupe=0
duplicates yet dedupe=1
, the results are different. BTW dedupe=1
looks like the default without setting dedupe
.
Perhaps Nominatim removes duplicates based on GPS and borders, not just place_id
?
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you can check the source code here . Basically, the parameter is dedupe
used to check if there is a duplicate in search results or not. it will be used when generating a query to get data from the database.
the parameters used when trying to check for duplication are place_id and address (country code, postal code, address, etc.). you can check the sql function in here (the function is called get_address_by_language
)
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I haven't heard of the parameter dedupe
, but I found your question while searching nominatim duplicate addresses
.
I am having a problem with some buildings existing twice in the Nominatim data, with slightly different address variations (e.g. Avenue vs Boulevard suffix, front door and back door as coordinates).
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