Overpass API developpement

[mmd <>]

Am 09.06.2015 um 19:15 schrieb Donal Diamond:
> On 9 June 2015 at 18:04, Malcolm Herring 
> <>
> wrote:

> 
>> 3. I intend to use an un-compressed db - does update_database require a
>> switch for this?
>>
> 
> AFAIK the new compressed db feature for .bin file is not optional - I don't
> think there is any switch.
> (The compressed .map file feature is still experiment and is in another
> branch)
> 

There's no command line switch to control compression. All relevant
settings are hardcoded in settings.cc [1]. If you plan to change it, you
need to recompile Overpass API with those new settings.

I haven't tested the following settings with 0.7.52 to get a
non-compression db again. Please give them a try and report back, if you
encounter any issues. Maybe you want to check with a small extract first.

  uint32 get_block_size() const { return block_size; }
  uint32 get_max_size() const { return 1; }
  uint32 get_compression_method() const { return File_Blocks_Index< TVal
>::NO_COMPRESSION; }

If performance is a concern: there's also the option to have a rather
low overhead compression using lz4, see my branch [2]. It runs on top of
Roland's backend_compression_map branch [3] and is currently also
deployed on the Overpass API dev instance for further testing.

Cheers,
mmd


[1]
https://github.com/drolbr/Overpass-API/blob/master/src/overpass_api/core/settings.cc#L51
[2] https://github.com/mmd-osm/Overpass-API/tree/compression_lz4
[3] https://github.com/drolbr/Overpass-API/tree/backend_compression_map