[postgis-users] Storage of GML as BLOBs

[Finn Hedefalk]

Dear all,

When using the new version of Deegree WFS (http://www.deegree.org/), a 
popular storage method seems to be to store GML files as BLOBs in the 
PostgreSQL/PostGIS XML data type. One reason is to avoid the complex 
(and time-consuming) mappings required from a complex database schema. 
BLOBs seems to be an easy method if the task is to quickly provide data 
that confirms to certain specifications, such as the ones from the 
INSPIRE directive. That is, the purpose of the database is to be an 
intermediate storage when providing  certain data (however, in your 
source database, data are not stored as BLOBs).

I believe this approach may enhance the performance when you only need 
to provide some few GML datasets. However, I assume that when you have 
large amounts of data, there may be, for example, (1) performance 
impacts when doing spatial queries; (2) harder to create spatial 
indexes; and (3) storage problems because GML BLOBs takes up more space.

Are these assumptions correct?

Kind regards
Fin