[mapserver-users] Grave performance issue with MapServer and GDAL/OCI driver

[Niccolo Rigacci]

I experienced a severe performance problem with MapServer 
configured as WFS server, taking data from Oracle via GDAL/OCI 
driver.

All the features take about 9.6 Mb of xml data (via WFS) or 8.4 
Mb of text data (via ogrinfo).

Retrieving all the features via WFS from a shapefile takes less 
than one second, retrieving the same WFS from Oracle takes about 
470 seconds. Retrieving data via the ogrinfo utility takes about 
3 seconds:

Tests are performed from the same Linux box, taking data in this 
way:

  1 s: wget <- http <- Remote_host <- MapServer <- GDAL <- shapefile
470 s: wget <- http <- Remote_host <- MapServer <- GDAL/OCI <- localhost <- Oracle
  3 s: ogrinfo <- GDAL/OCI <- Remote_host <- Oracle

It seems that wget (int the Oracle case) starts at about 400 
Kb/sec transfer rate, then it drops down to 13 Kb/sec a few 
seconds later.

Does somebody have any idea where is the bottleneck? How can I 
debug such slodown?

Software versions:
Oracle Instant Client 10g
GDAL: gdal-base-1.6.1-oci (from FGS Linux Installer)
MapServer 5.4.0 (from FGS Linux Installer)

This is the LAYER in the mapfile:

LAYER
  NAME "aree_stradali"
  STATUS DEFAULT
  TYPE POLYGON
  # Dati da connessione Oracle
  CONNECTIONTYPE OGR
  CONNECTION "OCI:username/secret at localhost/sitfi02t"
  DATA "REPLICA_TOPONOMASTICA.AGGR_AREESTRADA"
  # Dati da shapefile
  #DATA "shape/toponomastica/aree_strada.shp"
  PROJECTION
    "init=epsg:3003"
  END
  DUMP TRUE
  METADATA
    "wfs_title"     "aree_stradali"
    "gml_featureid" "objectid"
  END
  CLASS
    STYLE
      COLOR 255 0 0
      WIDTH 1
    END
  END
END



-- 
Niccolo Rigacci
Firenze - Italy