I too am very interested in this, as managing even a small number of tiles really becomes burdensome. A transfer of even a small number of tiles is significantly slower than a single file. <div><br></div><div>Having a sqlite file is nice - especially for portable applications - but is still nice for server and desktop applications. </div>
<div><br><div class="gmail_quote">On Mon, Apr 11, 2011 at 6:51 AM, Klokan Petr Pridal <span dir="ltr"><<a href="mailto:klokan@klokan.cz">klokan@klokan.cz</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hi Oliver,<br>
<br>
I am really looking forward to read the post on your mentioned<br>
subject: "design of a database schema for a new tile store format that<br>
<div class="im">supports multiple caches per database and also caches split into<br>
multiple databases".<br>
<br>
</div>There are indeed use-cases where this is exactly what is technically<br>
required. We use a similar (simplified) approach in-house and I would<br>
be very glad to standardize this and share our experience with other<br>
too.<br>
<br>
Please post your ideas and draft into this forum - I am sure it will<br>
be attractive for the readers and we can then discuss this subject<br>
further.<br>
<br>
Best regards,<br>
<br>
Klokan Petr Pridal<br>
<br>
(the author of GDAL2Tiles and MapTiler)<br>
<div><div></div><div class="h5"><br>
On Mon, Apr 11, 2011 at 2:29 PM, Oliver Tonnhofer <<a href="mailto:olt@omniscale.de">olt@omniscale.de</a>> wrote:<br>
> Hi Andreas,<br>
><br>
> On 11.04.2011, at 13:38, Andreas Trawoeger wrote:<br>
>> I'm not really sure if switching to SQLite is going to make tile-cache-management a lot easier in the long run. SQLite would be perfect for small and somewhat static tilestores or offline caches for mobile applications.<br>
>> But once they get bigger and have constant read & write access databases get notorously difficult to backup.<br>
><br>
> Thanks for raising some concerns. It's too easy to neglect the cons when discussing these things.<br>
><br>
>> Having thousand of files can be hard to handle. But there are myriad of tools like e.g. rsync that makes handling them a lot easier.<br>
><br>
> Copying thousands of small files is much slower then a few big files. I have a virtual machine where it takes 2.5 minutes to do a `du -sk cache_data` on 300.000 tiles. And 300.000 tiles is a small number. These are the issues when we are talking about manageability.<br>
><br>
> For managing SQLite files, there is a backup API that allows copying databases without locking issues. <a href="http://www.sqlite.org/backup.html" target="_blank">http://www.sqlite.org/backup.html</a><br>
><br>
> My database design provides support splitting a cache into multiple databases (e.g. one DB per resolution, or even multiple DBs for large tile sets (level > 16)). So for large caches you would have multiple files.<br>
><br>
> Regards,<br>
> Oliver<br>
><br>
> --<br>
> Oliver Tonnhofer | Omniscale GmbH & Co KG | <a href="http://omniscale.de" target="_blank">http://omniscale.de</a><br>
> <a href="http://mapproxy.org" target="_blank">http://mapproxy.org</a> | <a href="https://bitbucket.org/olt" target="_blank">https://bitbucket.org/olt</a> | @oltonn<br>
><br>
><br>
><br>
><br>
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<br>
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