main~
很简单,可以通过对比来理解概念。
实例,下面是C#提取器脚本。
public class MyTsvExtractor : Extractor
{
public override Schema Produces(string[] requested_columns, string[] args)
{
return new Schema(requested_columns);
}
public override IEnumerable<Row> Extract(StreamReader reader, Row output_row, string[] args)
{
char delimiter = '\t';
string line;
while ((line = reader.ReadLine()) != null)
{
var tokens = line.Split(delimiter);
for (int i = 0; i < tokens.Length; ++i)
{
output_row[i].UnsafeSet(tokens[i]);
}
yield return output_row;
}
}
}
对比于Scope脚本:
searchlog =
EXTRACT IId:int, UId:int, Start:DateTime, Market:string, Query:string, DwellTime:int, Results:string, ClickedUrls:string
FROM @In_SearchLog
USING MyTsvExtractor();