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Example Showing how CSV Provider will use chunks of a stream while iterating
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| #r "nuget:FSharp.Data" | |
| open System.IO | |
| open System.Text | |
| open FSharp.Data | |
| type Csv = CsvProvider<"A,B,C\n1,2,3", CacheRows=false> | |
| let csvStream = | |
| let stream = new MemoryStream() | |
| stream.Write(Encoding.UTF8.GetBytes("A,B,C\n")) | |
| for i in 1..500 do | |
| stream.Write(Encoding.UTF8.GetBytes($"{i},{i+1},{i+2}\n")) | |
| stream.Position <- 0 | |
| stream | |
| let mutable position: int64 = 0 | |
| for row in Csv.Load(csvStream).Rows do | |
| if position <> csvStream.Position then | |
| position <- csvStream.Position | |
| printfn $"A = {row.A}; B = {row.B}; C = {row.C}; StreamPosition = {csvStream.Position}" |
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| A = 1; B = 2; C = 3; StreamPosition = 1024 | |
| A = 112; B = 113; C = 114; StreamPosition = 2048 | |
| A = 197; B = 198; C = 199; StreamPosition = 3072 | |
| A = 283; B = 284; C = 285; StreamPosition = 4096 | |
| A = 368; B = 369; C = 370; StreamPosition = 5120 | |
| A = 453; B = 454; C = 455; StreamPosition = 5688 |
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Yes, my example does have the whole CSV in a
MemoryStreamjust to show how the file is being loaded in chunks without having to actually write to my file system (by printing theStream's position), but you can replace with aStreamReaderlike you have sinceLoadhas an overload for aTextReader.It turns out I'm the dummy today and forgot that you also need to set
CacheRowstofalsesince it actually defaults totrue:type Csv = CsvProvider<"A,B,C\n1,2,3", CacheRows=false>I updated the example above. Hopefully that works, that's what I get for not creating a 20GB file for myself to make extra sure it does what I think it does. 😆