VGF Loader API

const char * AllCreateVGF(const char *pXml)

return is non-zero on success or 0 for failure

Changes

As of Allocate 5.6.10 there is a new command within the Params

largeLoad

Set this to True if your load is very large (greater that 1,000,000 records or so) and the loader is running out of memory.  This will cause the load to work in chunks small enough to fit in memory.  The records MUST be presorted and the key lengths must all be the same.  It is also incompatible with optimize="true" and autoAssignParent="true".

buildAltKeyIndex

if this is true, it will build an AltKey index.  In order for this to work, all the keys must start with a special character, usually # and the AltKeys must never start with the special character.

Polygon based loads

Example XML

<CreateVGFFile type="Polygon">
	<InputFile
		path="c:\temp\ColoradoPlaces.tab"
		table=""
		nameField="Name"
		keyField="Key"
		altKeyField=""
		/>
	<OutputFile
		path="c:\temp\ColoradoPlaces.vgf"
		/>
	<Params 
		longName="Colorado Places"
		shortName="TEMP"
		parentShortName="COUNTY"
		autoGenerateKey="False"
		autoAssignParent="True"
		autoRegisterResult="True"
		autoUnregisterPrevious="True"
		optimize="False"
		/>
</CreateVGFFile>

AltKeyField

This is optional and will default to the same as the key.

AutoGenerateKey

if this is set to True, the KeyField will not be used.  The AltKeyField can still be used, but as always, is optional.

ParentShortName and AutoGenerateKey

If there is both a parent short name and AutoGenerateKey="True", the keys will be generated to fall within a parent when the centroid of the generated polygon falls within the parent.  This will be MUCH slower for most builds, especially when the VGF is for a small region, but the parent is national.

optimize

If True, it tries to roll up all the block groups into a tract or tracts into a county in order to minimize the data that is needed.  This will happen in the exact reverse of how the level is seen in the pick geography tree in the gui.  The default is set with by the data set.

Record based loads

Example XML

<CreateVGFFile type="Record">
	<InputFile
		path="C:\Temp\ZipVGFBuild\ZIP5Load.dbf"
		table=""
		nameField="Name"
		keyField="KEY"
		altKeyField=""
		percentHouseholdWeightField=""
		percentPopWeightField=""
		percentCountWeightField=""
		demoKeysShortNameField="KEY_TYPE"
		demoKeysKeyField="KEY"
		/>
	<SpatialInputFile
		path="C:\Temp\ZipVGFBuild\ZipVgfSpatialSource.tab"
		keyField="ZIPCODE"
		/>
	<OutputFile
		path="C:\Temp\ZipVGFBuild\ZIP5_1.vgf"
		/>
	<Params 
		longName="5 Digit Zip Codes"
		shortName="ZIP5"
		parentShortName="ZIP4"
		makeIntermediateVGF="False"
		createPolygons="False"
		autoAssignParent="False"
		autoRegisterResult="True"
		autoUnregisterPrevious="True"
		optimize="False"
		/>
</CreateVGFFile>

Household and PopWieghts

These are purely optional and will generally give proper results when left to the default behavior.

These are very complex issues and should not be used (and are not required) unless you know what you are doing.  It is possible to manipulate the demographic results such that they will be meaningless.  If HouseholdsWeight or PopWeight, both not both are specified, the other will be computed with the same ratio.  

percentCountField

This is a 0 to 1 percentage of the count of this record to pull.  If this is specified, but not Household or Pop Weight, then this percentage will be applied to the others and visa versa.

HideVGFInGUI

Use this for creating an intermediate layer in the hierarchy that is not in and of itself used to retrieve data.

CreatePolygons

If this is on, polygons will be merged and stored in the VGF file.  Any records that refer to only 1 DemoKeys Object will NOT store the polygon, as the polygon can be looked up at run time very quickly.

ParentShortName and AutoGenerateKey

See above.

This requires that CreatePolygons="True"

<SpatialInputFile ...>

If you use this, it requires that createPolygons=false.  You can use this to specify the polygons for a record based load.  The input file must be sorted by key, as well as the main input file must be sorted by key.  It supports .tab, .mid/mif .shp, .geo and .sdf if you have the autodesk sdf toolkit installed.  You can load points, lines or polygons into a VGF.

optimize

same as above except the default is always false for record based loads.

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