[postgis-users] Advice on space efficient grid indexing

[Martijn Meijers]

Hi Arnaud,

Would the idea of the Spatial Location Code help you?

http://www.gdmc.nl/oosterom/slc.pdf


Martijn


On 29-09-16 10:49, Arnaud L. wrote:
> Le 29/09/2016 à 10:11, Arnaud L. a écrit :
>> What would be a more efficient way to store this cell coordinates so
>> that disk usage would be limited and accessing the rows would be using
>> the index efficiently ?
>> Using a point geometry would not be space efficient I believe, and it
>> seems overkill since we do not need to do any spatial operation on this
>> column (only equality queries, i.e. retrieving all rows in a given 
>> cell).
>> I also thought about a bigint array of two elements, but our database is
>> mainly accessed through psqlodbc and I'm not sure that arrays are very
>> efficient in this case.
>
> I should also have pointed out that there is a third parameter, 
> because we have two overlapping grids (but a given geomtry can only be 
> in one of them). Sot it is more a 3 columns reference than a 2 columns 
> one.
> Also, the obvious choice of adding 3 columns (gridx, gridy, gridlevel) 
> would be that last choice, even after the ugly "char" column. We have 
> functions returning this "grid id", and it would be very inconvenient 
> if they should return setof bigints or records.
> I really like the idea that a grid cell has a unique "id" that can be 
> easily computed, and that a geometry can be also easily retrieved from 
> this id with having to write complex sql like (gridx, gridy, 
> gridlevel) = (..., ..., ...).
>
> Regards
> -- 
> Arnaud
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