[postgis-users] indexing images stored in PostGres

[Paul Ramsey]

My religious objections are that the use cases described for rasters in 
the database don't actually get any leverage from the database 
infrastructure.  The pgRaster model, for example, is basically a direct 
mapping of "bunch of tiffs on the file system" in a pretty relational 
model. But apps get no particular advantage out of the RDBMS model that 
they wouldn't equally receive from just using LibTIFF to access TIFFs.

Why store rasters in a database?
- Because it will be faster? No. In fact, a member of this list did the 
research and could not find a single storage method, BLOB, Objects, 
ByteA, relational, that was faster than just doing file access.
- Because it will be easier to manage? Just storing the metadata about 
your images in the database, and leaving the images elsewhere achieves 
this affect, without adding the overhead of dealing with terrabytes of 
data opaquely stored in the database.
- So you can do raster analysis in the database? I can see the validity 
in this, for the same reason doing vector analysis in the database is 
powerful. The database serves as an integration point between vector, 
raster, and attribute processing functionality.

Storing imagery in the database, solely for the purposes of extracting 
it later to draw on a map, that strikes me as pointless.


P.

William Kyngesburye wrote:
> I'm curious about rasters in PostGIS also.  I heard about PGRaster at 
> FOSS4G.
> 
> What about these 'religious objections'?  Or at least, can you describe 
> the pros and cons? or all cons ;)
> 
> On Oct 2, 2007, at 1:45 PM, Paul Ramsey wrote:
> 
>> Those of you still breathless at the opportunity to store your images 
>> in the database entirely (fools!) feel free to review Xing Lin's work 
>> in this branch. It's good work, though obviously I have religious 
>> objections to it... :)
>>
>> http://svn.refractions.net/postgis/branches/gSoC2007_raster/
> 
> -----
> William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
> http://www.kyngchaos.com/
> 
> "Oh, look, I seem to have fallen down a deep, dark hole.  Now what does 
> that remind me of?  Ah, yes - life."
> 
> - Marvin
> 
> 


-- 

   Paul Ramsey
   Refractions Research
   http://www.refractions.net
   pramsey at refractions.net
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   Cell: 250-885-0632