[Tilesathome] t at h server performance

[mkalkal]

Christopher Schmidt wrote:
> On Sat, Dec 22, 2007 at 11:10:03AM -0500, Milenko wrote:
>   
>> Pardon my ignorance, but what is the purpose of this database of blank 
>> tiles?  I'm just curious, as I know little to nothing about what the t at h 
>> server does and how it does it.  Is there a wiki page anywhere that 
>> explains how the infrastructure works?
>>     
>
> Rather than storing millions of 300 byte blank images, any time a blank
> image is encountered, it stores a row in a table saying 'this tile is
> blank (sea|land)'. At request time, if no tiles exist on disk, the tile
> is looked up in the database, and if the tile in the database is there,
> an appropriately colored blank image is returned instead.
>   
May be something like this:
Instead of keeping this information in database ,make a "bitmap" file of 
all tiles ,one byte for tile. Treat the file like two
dimensional array , so lookup will be very fast. Of course a semaphore 
is needed to ensure data integrity. For zoom level 17
file will be about 17 Gb . For other zoom levels files will be smaller.


Regards
Maciek Kaliszewski



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