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U-SQL user-defined objects overview

  • Artikkeli

U-SQL: user-defined objects: UDO

U-SQL enables you to define custom programmability objects, which are called user-defined objects or UDO.

The following is a list of UDO in U-SQL:

  • User-defined extractors

    • Extract row by row
    • Used to implement data extraction from custom structured files

  • User-defined outputters

    • Output row by row
    • Used to output custom data types or custom file formats

  • User-defined processors

    • Take one row and produce one row
    • Used to reduce the number of columns or produce new columns with values that are derived from an existing column set

  • User-defined appliers

    • Take one row and produce 0 to n rows
    • Used with OUTER/CROSS APPLY

  • User-defined combiners

    • Combines rowsets--user-defined JOINs

  • User-defined reducers

    • Take n rows and produce one row
    • Used to reduce the number of rows

UDO is typically called explicitly in U-SQL script as part of the following U-SQL statements:

  • EXTRACT
  • OUTPUT
  • PROCESS
  • COMBINE
  • REDUCE

Note

UDO’s are limited to consume 0.5Gb memory. This memory limitation does not apply to local executions.

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