[mapguide-internals] MapGuide RFC 112 - sqlite based tile cache

[Zac Spitzer]

answers inline

On Thu, May 12, 2011 at 12:56 AM, Traian Stanev
<traian.stanev at autodesk.com> wrote:
>
> Hi Zac,
>
>
> "Generating tiles is currently done using a rather brute force approach, by storing tiles in a database, it can be queried for existing tiles and only missing tiles can be requested."
>
> What do you mean by brute force? Doesn't tile existence checking come down to a file existence check?

By brute force, I mean that if mapguide goes down in the middle of
seeding the tile cache,
every tile needs to be requested again, which involves a lot of http overhead.

>
> "Using a sqlite database will use less disk space than a disk based tile cache."
>
> Do you have some numbers about the expected improvement? Inside its file, SQLite is basically a file system which will exhibit incomplete page filling and overflow, similar to a regular file system.

Individual files waste a lot of disk space, depending on the tile size
and file system block size,
I'm not a expert on this, but I'd expect a sqlitedb to be much more
efficent. Similiar to
what would be achieved by zipping up a tilecache with zero compression.

>
>
> Traian
>
>
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Zac Spitzer
> Sent: Saturday, May 07, 2011 3:12 AM
> To: MapGuide Internals Mail List
> Subject: [mapguide-internals] MapGuide RFC 112 - sqlite based tile cache
>
> http://trac.osgeo.org/mapguide/wiki/MapGuideRfc112
>
> --
> Zac Spitzer
> Solution Architect / Director
> Ennoble Consultancy Australia
> http://www.ennoble.com.au
> http://zacster.blogspot.com
> +61 405 847 168
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>



-- 
Zac Spitzer
Solution Architect / Director
Ennoble Consultancy Australia
http://www.ennoble.com.au
http://zacster.blogspot.com
+61 405 847 168