[mapserver-users] OGR and MSSQL non-specific error

[Anzel, Phil - NRCS, Fort Collins, CO]

Hi, Tamas,

I believe there is at least one bug in the OGR code: the SRID is not properly retrieved from the underlying Sql Server 2008 database or its value is ignored, and therefore zero records are returned.

Consider this Layer definition:
  LAYER
    NAME 'States'    STATUS ON
    PROJECTION 'proj=latlong' 'ellps=GRS80' 'datum=NAD83' END
    CONNECTIONTYPE OGR
    CONNECTION 'MSSQL:server=xxx;database=Navigation;uid=yyy;pwd=zzz;tables=NAV_STATE(ShapeGeometry)'
    PROCESSING 'CLOSE_CONNECTION=DEFER'
    DATA 'NAV_STATE'
    TYPE POLYGON
    CLASS
      STYLE
        OUTLINECOLOR '#e1dd00'
        WIDTH 2
      END
    END
  END

The ShapeGeometry has a non-zero SRID, as evidenced by a query executed against the database via Sql Server Management Studio (SSMS):
   select top 1 ShapeGeometry.STSrid from dbo.NAV_STATE
    -- that returns 4269

Using SSMS’ Activity Monitor, executing SHP2IMG with a mapfile containing the above LAYER causes the following query to be issued to Sql Server:
  select
    [OBJECTID], [ShapeGeometry], [AREA],
    [STATE_NAME], [STATE_FIPS], [SUB_REGION], [STATE_ABBR],
    [POP1990], [POP1997], [POP90_SQMI], [HOUSEHOLDS], [MALES],
    [FEMALES], [WHITE], [BLACK], [AMERI_ES], [ASIAN_PI], [OTHER],
    [HISPANIC], [AGE_UNDER5], [AGE_5_17], [AGE_18_29], [AGE_30_49],
    [AGE_50_64], [AGE_65_UP], [NEVERMARRY], [MARRIED], [SEPARATED],
    [WIDOWED], [DIVORCED], [HSEHLD_1_M], [HSEHLD_1_F], [MARHH_CHD],
    [MARHH_NO_C], [MHH_CHILD], [FHH_CHILD], [HSE_UNITS], [VACANT],
    [OWNER_OCC], [RENTER_OCC], [MEDIAN_VAL], [MEDIANRENT], [UNITS_1DET],
    [UNITS_1ATT], [UNITS2], [UNITS3_9], [UNITS10_49], [UNITS50_UP],
    [MOBILEHOME], [NO_FARMS87], [AVG_SIZE87], [CROP_ACR87],
    [AVG_SALE87]
  from dbo.NAV_STATE
  where [ShapeGeometry].STIntersects(
    geometry::STGeomFromText(
     'POLYGON((-126 22.1993540334789,
               -66 22.1993540334789,
               -66 51.1734146762311,
               -126 51.1734146762311,-126 22.1993540334789))',0)) = 1

Note that the STIntersects function is given an SRID argument of 0. This results in a return of zero records.

I also note that all columns are returned. That is unfortunate, as that could potentially represent quite a bit of network traffic,

- Phil

From: Tamas Szekeres [mailto:szekerest at gmail.com]
Sent: Monday, February 27, 2012 2:59 PM
To: Anzel, Phil - NRCS, Fort Collins, CO
Cc: mapserver-users at lists.osgeo.org
Subject: Re: [mapserver-users] OGR and MSSQL non-specific error


2012/2/26 Anzel, Phil - NRCS, Fort Collins, CO <Phil.Anzel at ftc.usda.gov<mailto:Phil.Anzel at ftc.usda.gov>>

1. Note that I omitted the “tables=…” as it appears that naming a specific table would interfere with connection pooling if I’m using many layers drawing data from different tables. Do I understand the role of the “tables=…” incorrectly?


Yes, it may be considered as being a different connection if the tables section is used.


2. I added the explicit spatial filtering (STIntersects…). Is there a better way to do this?


It seems to be a bit complicated this way. I think you should try simply setting the layer name in the DATA section. In this case the spatial filter is added automatically by the MapServer OGR driver.

Best regards,

Tamas

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