FIFO virtual processors

The database server uses FIFO virtual processors (VPs) to read and write to external tables on named pipes.

The default number of FIFO virtual processors is 1.

The database server uses one FIFO VP for each named pipe that you specify in the DATAFILES clause of the CREATE EXTERNAL TABLE statement. For example, suppose you define an external table with the following SQL statement:
   SAMEAS items
   USING (
If you use the default value of 1 for FIFO VPs, the database server does not read from pipe2 until it finishes reading all the data from pipe1, and does not read from pipe3 until it finishes reading all the data from pipe2.
Note: If you create multiple external tables with pipes, concurrent operations on such tables can create dependencies between the pipes. To avoid this, enable automatic tuning for FIFO VPs. If there is no VPCLASS parameter for FIFO VPs, then the AUTO_TUNE setting controls the automatic tuning.

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