[Tilesathome] Proposal: Keeping tileset as one file

[Jiri Klement]

I didn't mean  to just replace zip with something easier. I meant to
send all tiles for one layer in one file and keep that file on the
server. Don't extract png files.

Currently there is about 1000 png files for one z12 tileset. I propose
to keep all these pngs in one file file with simple structure.


Btw. At first I've sent this to Alan only. Wouldn't it be better to
configure list to include reply-to: tilesathome at openstreetmap.org
header?


On 6/5/08, Alan Millar <am12 at bolis.com> wrote:
> Jiri Klement writes:
>
>  > What do you think about keeping the whole tileset (for z12) in one file?
>
>
> Interesting idea.
>
>
>  > Uploading will be much easier than now, it will just save file
>  > uploaded by client to correct place, no zip extraction will be
>  > necessary.
>
>
> Hmm; I don't think it is really any easier or different.  You need custom
>  code to write the tile into the proper position in the upload file in the
>  client, and the reverse to extract it on the server.  How is that any
>  easier than a zip file?  I haven't heard of any of the software having any
>  trouble with zip files.  Either way, on the server you are unpacking
>  several files from one file; you aren't getting around that.
>
>
>  > Performance - uploading will get definitely faster.
>
>
> That is sort of true, for the immediate results on one z12 tile.  Right
>  now, if you upload each layer separately, like the current default
>  behavior, then you see lots of waiting in between steps in the tile
>  processing.
>
>  However, if you want it to upload all layers for one z12 tile in a single
>  upload, you can already do that using zip.  If you use the existing
>  tilegen process and save the tiles until the end, and combine them all in
>  a single zip file, then you have the exact same speedup as you are
>  proposing.  With the advantage that none of the file handling on the
>  server has to change at all.
>
>  Try it with  ./tilesGen.pl --LayerUpload=0 xy ....
>  and then you can zip them all up at the end.  Use   zip -j
>
>  (If you are concerned about the negligible performance impact of the
>  compression handling in the zip/unzip, the zip can be used as just a
>  container without compression.  See "zip -0" for example.)
>
>  The bottome line, though, is that the speedup in either case is an
>  illusion.  It gets it off your machine sooner into the upload queue, which
>  bogs down that much more.  You still have to wait that much longer to be
>  able to get the next tile uploaded into the queue.  None of this changes
>  how many tiles the server can process in 24 hours.  It just means that you
>  will see "No work for you; upload queue is full" more often than you do
>  now.
>
>  - Alan
>
>
>
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