Neoview Query Guide (R2.3, R2.4, R2.5)

• “PARTITION_ACCESS Operator” (page 22)
• “SPLIT_TOP Operator” (page 23)
It is important to be able to identify the process in which an operation occurs. Process boundaries
are identified by these operators:
• ROOT operator. This operator and all operators under it execute inside the master executor
(also called root process) until another process boundary is reached. Operators that can
execute within the master executor process include sort, groupby, union, join, and some of
the miscellaneous operators.
• ESP_EXCHANGE operator. This operator operates partially in the master process and
partially in the executor server process (ESP). All operators under it execute inside an ESP
process or until another process boundary is reached. This operator represents the transfer
of data between two sets of processes: bottom processes that produce output rows and top
processes that receive the rows produced by the bottom processes. Operators that can execute
within the ESP process include sort, groupby, and join operators.
• PARTITION_ACCESS operator. This operator operates partially in the master/ESP process
and partially in the DAM process. All operators under it execute within a DAM process.
Operators that can execute within the DAM process include scan and groupby operators.
NOTE: Data Access Manager (DAM) is the disk process. DP2 is also used to represent the
disk process.
This example shows a partial plan in NPA with the process boundaries identified by color. The
gray shading indicates operators that operate within the root or master process. The yellow
shading indicates operators that operate in the DAM process. All other colors indicate ESP
processes.
Operators and Description Fields 19