[fdo-users] Improving performance for NEN1878 provider, howto?

Piet Bibber piet.bibber at gmail.com
Mon Oct 1 07:46:11 EDT 2007


My NEN1878 provider is almost done, but performance is not so fantastic when
reading the geometry; reading the schema is alright.
That is stange, as I cache in the geometry when I read the schema (NEN1878
schema discovery requires a full file scan; no seperate schema header). (The
schema is read within 3 seconds for a 2.3MB file, including the geometry and
attributes (all in memory (using STL)).
The SDF and SHP all seem so fast :-)

Map 3D seem to spend most of his time caching in the geometry (see source
code below)

I based my provider on the SHP provider, the reader seem to use FDO_READER
template, but I can't find where that points to. Maybe there are better
optimized readers.


Excerpt from the source files:

    FdoByteArray * CreateCachedGeometry(FdoByteArray* fgfByteArray_I)
        FdoByteArray*   fgfByteArray = fgfByteArray_I; // it may be
        int             count = mFeature->GetNumPoints();
        FdoInt32        numPointOrds = 2;
        FdoInt32        numBytesForOrdinates = numPointOrds * sizeof(double)
* count;
        FdoInt32        numParts = 0;
        FdoGeometryType fdoGeomType  = GetFdoGeometryType();
        FdoInt32        dimensionality = FdoDimensionality_XY;
        FdoInt32        numPositions   = mFeature->GetNumPoints();


        fgfByteArray = FdoByteArray::Append(fgfByteArray,
sizeof(fdoGeomType), (FdoByte *) &fdoGeomType);
        switch (fdoGeomType)
        case FdoGeometryType_None:

	    case FdoGeometryType_Point:
            fgfByteArray = FdoByteArray::Append(fgfByteArray,
sizeof(dimensionality), (FdoByte*)&dimensionality);
            fgfByteArray = FdoByteArray::Append(fgfByteArray,
numBytesForOrdinates,   (FdoByte*)mFeature->GetPoints());

	    case FdoGeometryType_LineString:
            fgfByteArray = FdoByteArray::Append(fgfByteArray,
sizeof(dimensionality), (FdoByte *) &dimensionality);
            fgfByteArray = FdoByteArray::Append(fgfByteArray, sizeof(count),
(FdoByte *)&count);
            fgfByteArray = FdoByteArray::Append(fgfByteArray,
numBytesForOrdinates, (FdoByte *)mFeature->GetPoints());


	    return (fgfByteArray);

// Returns pointer to vector of DoublePoints
inline DoublePoint* Nen1878Feature::GetPoints()
    return (&mCoordinates[0]);

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