[postgis-users] [slightly off-topic] Question on build a C address parse for an embedded geocoder

[Stephen Woodbridge]

Hi Dev's,

I am interested in writing an address standardized in C that could be 
callable from SQL. I understand the basics of doing this from supporting 
pgRouting and writing some additional commands. It would get used 
something like:

select * from standardize(address, city, state, country, postcode);
select * from standardize(address_one_line);

and would return a standardized set of fields like: house_num, street, 
city, state, country, postcode. These could be then used to create 
standardized reference table or it could be passed into the geocoder 
that would search the standardized reference table.

What I am struggling with is how to best initial the address 
parser/standardize. The concept I have in mind is to have some tables 
that represent the lexicon, gazetteer, parsing rules, etc. This data 
could be specific to country and/or country-state. I could be fairly 
small or quite large. For example, there are about 40K unique city names 
based on the USPS zipcodes and about 7K of them have duplicate 
standardizations based on state.

On the one hand I can read these tables on every request and build the 
internal structures, parse the request, and throw out the internal 
structures.

Basically once the reference source records have been standardized you 
should not be changing the above tables because you want to standardize 
future search requests based on the same rules that the reference road 
segments were standardized.

And ideally you do not want to spend the time to rebuild these internal 
structures on every search request.

So is there a mechanism for building some internal data and holding on 
to it between requests. I suppose I could store it in a blob, but it 
would then need to be de-toasted on every search request.

Maybe, I'm this is an non-issue, but it seems to impact the design 
depending on what options I might have and how they are implemented and 
accessed from the code.

Thoughts?

Thanks for any help or suggestions,
   -Steve W