[OSM-dev] OSM Database schema

[Lorenzo Stucchi]

Thank you, Martin.

This is exactly what I was searching for. In the meanwhile, I put all the table in the wiki table if someone is interested in complete the description of the full schema. 

Best,
Lorenzo

> Il giorno 14 gen 2020, alle ore 11:25, Martin Raifer <tyr.asd at gmail.com> ha scritto:
> 
> I believe the formula just implements the interleaving of the X and Y
> coordinates used in the QuadTiles[1] indexing schema in an efficient
> way by using some clever bit operations.
> 
> [1] https://wiki.openstreetmap.org/wiki/QuadTiles#Quadtile_implementation
> 
> On Tue, Jan 14, 2020 at 11:11 AM Lorenzo Stucchi
> <lorenzostucchi95 at outlook.it> wrote:
>> 
>> Hi all,
>> 
>> I have almost complete the explanation of the schema regarding the element (node, way and relation) I have just one last element to be understood.
>> 
>> The “tile” in the node table. I found in the code a function called “public.tile_for_point” [1] and seems that should be the one that do this process. But I’m not able to understood which is the output of the function, in particular what this part of code does:
>> 
>> x := (x | (x << 8)) & 16711935; — 0x00FF00FF
>> 
>> Thanks for all the reply.
>> 
>> Best,
>> Lorenzo
>> 
>> [1] https://github.com/openstreetmap/openstreetmap-website/blob/751e8ad32c864f50eae9e9359d74a11dc44de007/db/structure.sql#L160
>> 
>> Il giorno 10 gen 2020, alle ore 15:51, Lorenzo Stucchi <lorenzostucchi95 at outlook.it> ha scritto:
>> 
>> Thanks for the reply.
>> 
>> Is this the formula [1] ?
>> 
>> Best,
>> Lorenzo
>> 
>> [1] https://github.com/openstreetmap/openstreetmap-website/blob/751e8ad32c864f50eae9e9359d74a11dc44de007/db/structure.sql#L160
>> 
>> Il giorno 10 gen 2020, alle ore 15:22, Frederik Ramm <frederik at remote.org> ha scritto:
>> 
>> Hi,
>> 
>> On 10.01.20 15:08, Lorenzo Stucchi wrote:
>> 
>> What does it mean the “timestamp” present in the table (“node", “way" and “relation")?
>> 
>> 
>> When the object was last changed.
>> 
>> What does it mean the “tile” element present in the “node" table?
>> 
>> 
>> An integer derived from the lat/lon of the node using a mathematical
>> formula.
>> 
>> What does it mean the “sequence_id” in the “way_nodes” table and “relation_member” table?
>> 
>> 
>> An integer used to store the ordering of the nodes/members (which node
>> is the first, the second, ... in the way).
>> 
>> Bye
>> Frederik
>> 
>> --
>> Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"
>> 
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