Mateusz Łoskot wrote:[...] I do too. I use ESRI Shape as tha main vector data format and SQLite as descriptive (extensible attributes) data storage format. But I think the best solution would be to store all sorts of data (geometries and descriptive) in SQLite database such as it is working in PostgreSQL/PostGIS.
Yes I am moving to this model too, I can mix "traditional" level with spatial data in memory and attribute in sqlite, and db level with everything in sqlite. Even edition works, and if done inside a transaction , rollback gives you a nice graphic undo !
Currently it seems to be the easiest way of GIS implementation using ESRI Shapes and SQLite together. But I believe that isn't a limit of SQLite possibilities ;-)))
[...] I know that Indexing is still a problem in spatial data even using SQLite. The performance problem could be in enc-/decoding binary stored geometries i.e. in Well-Known-Binary format.
Yes that is what I mean by using uuencode or yenc for that matter.
Also OpenGIS Well-Known-Text format for geometries stored in SQLite tables may not be the best solution. I still think binary encoded data would be the best for performance. In example, calculating length of LineString (curve) from WKT: 1. Find record in table (simple, one SELECT statement, nothing genius) 2. Read geometry in WKT (field dedicated for geometries, i.e. special type i.e. Geometry) 3. Calculate length of LineString just retrieved
All these 3 steps would be taken in 1 if proper support would be available in SQLite i.e.:
SELECT LENGTH(MyGeometryField) AS LEN FROM MyTable WHERE .....
But if geometries are stored as WKT there have to be taken additional steps: parsing WKT string and retrieving coordinates. WKT string for LineString is LINESTRING(x1 y1,x2 y2,...,xn yn)
Parsing such strings may decrease speed of calculation significantly. But if geometries are stored in WKB (binary) then it should run faster I think.
I'm ready to collaborate if it can be of mutual benefit :-)[...] So, it should be tested ;-)) Now, I'm making some researches.
Certainly, if I think about any work on that, I think about the Open Source model like SQLite. But I'm bound to say that I haven't done any serious design work on that. I think about that but I realize that it needs such effort.
Regards
-- Mateusz Łoskot, mateusz at loskot dot net GNU/Linux (Slackware 9.1) http://counter.li.org #220771
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