One of the major differences between .Net and VFP is that even when working against SQL Server the "cursor" in VFP is held in a temporary dbf (which for large datasets we actually point toward an imdisk ramdisk: nothing is faster than memory). In .Net, a recordset is help in memory. That's fine for small datasets, but datasets for reporting (munged from what's available on the backend server) can be quite large. It will be interested to see speed differences between the two approaches.
Hank
>Hi Daniel,
>
>> Thanks for this great clarification on Xsharp vs VFP and all the stuff you provided lately.
>You are more than welcome, and also thanks a lot for your participation!
>
>> I imagine that could be:
>> - use something like an "in memory sqlite engine" (a typical solution for C-based python),
>> - some linq-related technology...
>Well I think this is maybe the two aspects I will address in this response...
>
>Linq is already supported in both Linq and Lambda format:
>
>LOCAL dPot AS System.Func<Prop, List<Prop> >
>dPot := ;
> { p AS Prop =>
> VAR Potentials := List<Prop>{}
> VAR pcs := 0
> Potentials:Add(p)
> LOCAL oP AS Prop
> REPEAT
> oP := Prop{p:Name, p:Quantity, p:Price}{Pieces := ++pcs}
> Potentials:Add(oP)
> UNTIL Prop.Qualify(oP:Constraint())
> RETURN Potentials
> }
>VAR oPot1 := dPot(oP1)
>VAR oPot2 := dPot(oP2)
>VAR oPot3 := dPot(oP3)
>
>VAR oSol := (FROM p1 IN oPot1 ;
> JOIN p2 IN oPot2 ON TRUE EQUALS TRUE ;
> JOIN p3 IN oPot3 ON TRUE EQUALS TRUE ;
> WHERE Prop.Qualify(p1:Constraint() + p2:Constraint() + p3:Constraint()) ;
> ORDERBY (p1:Minimize() + p2:Minimize() + p3:Minimize()) ;
> SELECT <INT>{p1:Pieces, p2:Pieces, p3:Pieces}):Take(3)
>>
>Regarding in memory "SQLite", I am busy looking at converting the following ArrayServer class from Visual Objects to X#. The DevTeam has indicated after SWFOX the VFP Cursor will get priority, this might be the basis of it realising...:
>
>CLASS ArrayServer INHERIT DataServer
> /* The following IVars inherit from DataServer:
> aClients // Array with all Notify-Clients
> aDataFields // Array with DataField object for each column
> nCCMode // Concurrency mode
> nLastLock // ???
> oHLStatus // HyperLabel identifying the status after the last operation
> oHyperLabel // HyperLabel of the Server
> wFieldCount // Number of columns
> */
> PROTECT _aData AS ARRAY // Two dimensional Array with the data
> PROTECT _wRecNo AS WORD // Current row
> PROTECT _wLastRec AS WORD // Number of rows
> PROTECT _aDeleted AS ARRAY // Deleted flags for _aData
> PROTECT _lEoF AS LOGIC // EoF flag
> PROTECT _lBoF AS LOGIC // BoF flag
> PROTECT _aRecord AS ARRAY // Buffer for the current record
> PROTECT _lSetDeleted AS LOGIC // SetDeleted() state for this server
> PROTECT _aNewRec AS ARRAY // Default values for new records
>
> // We emulate the DbServer class, so add these also to the class
> PROTECT aStruct AS ARRAY
> PROTECT siSuspendNotification AS SHORT
>
> /* I think the following Messages are automatically handled by DataServer,
> because we use the inherited PROTECT intance variables, particularly
> aDataFields.
>
> PROPERTIES
> ConcurrencyControl Access/Assign
> FCount Access
> HyperLabel Access/Assign
> Name Access
> NameSym Access
>
> METHODS
> AsString
> DataField
> Commit
> FieldHyperLabel
> FieldName
> FieldPos
> FieldSpec
> FieldStatus
> FieldValidate
> NoIvarGet
> NoIvarPut
> RegisterClient
> UnregisterClient
> */
> METHOD Append() CLASS ArrayServer
> ACCESS DBStruct CLASS ArrayServer
> METHOD Close() CLASS ArrayServer
> METHOD Commit() CLASS ArrayServer
> ACCESS Data() CLASS ArrayServer
> METHOD DefaultValue( uFieldID ) CLASS ArrayServer
> ACCESS BoF CLASS ArrayServer
> METHOD Delete() CLASS ArrayServer
> ACCESS Deleted CLASS ArrayServer
> ACCESS EoF CLASS ArrayServer
> METHOD FIELDGET( uFieldID ) CLASS ArrayServer
> METHOD FieldGetFormatted( uFieldID ) CLASS ArrayServer
> ACCESS LASTREC() CLASS ArrayServer
> METHOD Notify( kNotifyName, uDescription ) CLASS ArrayServer
> METHOD Recall() CLASS ArrayServer
> METHOD RecallAll() CLASS ArrayServer
> ACCESS RecCount CLASS ArrayServer
> ACCESS RecNo CLASS ArrayServer
> ASSIGN RECNO( nNewRec ) CLASS ArrayServer
> METHOD Refresh() CLASS ArrayServer
> METHOD ResetNotification() CLASS ArrayServer
> ASSIGN SetDeleted( lDeleted ) CLASS ArrayServer
> METHOD Skip( nSkip ) CLASS ArrayServer
> METHOD SuspendNotification() CLASS ArrayServer
> DEFINE MAX_ARRAY := 65535
> METHOD FieldPos( uFieldID ) CLASS ArrayServer
> METHOD FIELDPUT( uFieldID, uValue ) CLASS ArrayServer
> METHOD GoBottom() CLASS ArrayServer
> METHOD GoTo( nNewRec ) CLASS ArrayServer
> METHOD GoTop() CLASS ArrayServer
> METHOD Init( aArrayStruct, aDataArray ) CLASS ArrayServer
>END CLASS
>
>
>> Hope my post was clear enough. Language design is not my thing!
>Loud and clear
