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Asked: 2026-05-28T05:45:13+00:00

I am setting up a location aware application, as mentioned here . I have

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I am setting up a location aware application, as mentioned here. I have since learned a lot more about GIS apps, and have decided to change a few things about the setup I had originally proposed — I’m now going to use a postgresql database using the postgis extension to allow for geometric fields, and use TIGER/Line data to fill it. The TIGER/Line data seems to offer different data sets in different resolutions (layers) — there is data for states, counties, zips, blocks, etc. I need a way to associate a post to an address using the finest grain resolution possible.

For instance, if possible, I would like to associate a post with a particular street (finest resolution). If not a street, then a particular zip code (less specific). If not a zip code, then a particular county (less specific), and so on. Sidenote: I want to eventually show these all on a map.

This is what I propose:

Locations

id              -- int
street_name     -- varchar  -- NULL
postal_code_id  -- int      -- NULL
county_id       -- int      -- NULL
state_id        -- int

Postal Codes

id      -- int
code    -- varchar
geom    -- geometry

Counties

id      -- int
name    -- varchar
geom    -- geometry

The states table is similar, and so on…

As you can see, the locations table would decide the level of specificity by whatever fields are set. The postal codes, counties, and states table are not tied together by foreign key (too complex to determine a proper hierarchy that is valid everywhere), however, I believe that there is a way to determine their relationship using the geometry field (e.g., query what state a certain zip code is contained in or what zip codes belong to a certain state).

I think this is a good setup because if the database grows (lets say I decide to include data for districts or blocks in the database) then I can add another table for that data and then add another foreign key to the locations table (eg, block_id).

Does anybody know of a better way to do this?

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1 Answer

  1. Editorial Team

    Is it possible that a street belongs to two different counties? or two postal codes?, In my country this is possible, specially in cities. If this is possible then your schema won’t work.

    Despite of what I said before, I would add the geometry of the streets(open street map) without linking it to a postal code or county or even the state, and then with a simple query that intersects the geometry of the streets with the other tables you could get that information, and fill another table that has that relationships.

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