Caching when updating mbtiles in Martin

[jjcfrancisco]

I am using Martin with mbtiles and one of them is the planet mbtiles. If I update the planet mbtiles file, is the only way for Martin to pick up the changes to restart the server?

[nyurik]

yes and no - mbtiles is a sqlite db - so if caching is disabled, it might actually be able to pick it up directly... That said, I would advise not to do it because sqlite is not usually recommended for read/write access from multiple processes. Instead, you can do the same thing relatively easily with a postgres db (i.e. just store things as blobs). On the other hand, for small installs / low usage, you might get away without having a proper server.

To do this in PostgreSQL, simply set up a table with z, x, y, data columns, and write a function that takes z,x,y and returns data. This is very similar to the structure of the mbtiles itself. You may want to use non-flat structure too, but it is slightly more complicated (but may save some disk space).

[jjcfrancisco]

This is it. Thanks @nyurik

[jjcfrancisco]

@nyurik just for clarity and also anyone else who may be wondering, I presume to have the alternative setup via Postgres bytea in the config.yaml would be as a PG source and not as a mbtiles source?

# Here my Martin configs...

postgres:
  connection_string: '${DATABASE_URL:postgresql://postgres@localhost:5432/db}'
  default_srid: 4326
  pool_size: 20

  functions:
    get_bytea_data:
      schema: public
      function: get_bytea_data
      minzoom: 0
      maxzoom: 21

[nyurik]

yes, you can have a postgres database with all the needed data, and write a function as described in the book that returns a tile. That function could be arbitrary complex, including ability to cache entire tile (bytea blob) in some table rather than re-generating it on every request.