SQL/MX 3.1 Query Guide (H06.23+, J06.12+)

SQL/MX Operators
HP NonStop SQL/MX Release 3.1 Query Guide—663851-001
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ESP_EXCHANGE Operator
The following is an example of the ESP_EXCHANGE operator:
create table tabl3 (a int, b int, c int, d int, e int);
create table tabl4 like tabl3;
Token Followed by ... Data Type
fragment_id A sequential number assigned to the
fragment. 0 is always the master
executor and 1 is reserved for the
EXPLAIN plan. Numbers 2 to n will be
ESP or DAM fragments.
integer
parent_frag The fragment_id for the parent of the
current fragment. The value is (none)
for the master executor.
integer
fragment_type Master, ESP, or DP2. text
buffer_size Size of message buffer. integer
record_length Number of bytes in the record sent. integer
parent_processes Indicates the number of processes that
the ESPs in the ESP_EXCHANGE
operator communicates with either
additional ESPs (as indicated by
another ESP_EXCHANGE operator) or
the master process.
integer
child_processes Indicates the number of processes that
supply the ESPs of an operator with
rows. The number of ROWS_OUT
(also called CARDINALITY) from the
operator that supplies the
ESP_EXCHANGE operator with data
indicates how many rows the
ESP_EXCHANGE operator is
expected to receive.
integer
parent_partitioning_function Type of top partitioning and contains
summary information about the parallel
plan.
text
child_partitioning_function Indicates how the input data received
by the ESP_EXCHANGE operator is
organized.
text
merged_order Expression describing sort keys used
to control the interaction between the
parent process (usually the master)
and ESPs when the result is ordered.
expr(text)
bottom_partition_input_values Internal values that identify the part of
the data the ESP will work on.
text
partitioning_expression Expression used to partition data. expr(text)
TP663851.fm Page 13 Monday, October 17, 2011 11:48 AM