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The DETAIL_COST column of the EXPLAIN function results contains these cost factors:
CPU_TIME
IO_TIME
MSG_TIME
IDLETIME
PROBES
Examples of EXPLAIN Function
•
Display the specified columns in the result table of the EXPLAIN function for the prepared
statement REGION:
>>select seq_num, operator, operator_cost from table (explain (null, 'REG'));
SEQ_NUM
-----------
--- 4 row(s) selected.
>>log;
The example displays only part of the result table of the EXPLAIN function. It first uses the
EXPLAIN function to generate the table and then selects the desired columns.
An estimate of the number of seconds of processor time it might take to execute the
instructions for this operator. A value of 1.0 is 1 second.
An estimate of the number of seconds of I/O time (seeks plus data transfer) to
perform the I/O for this operator.
An estimate of the number of seconds it takes for the messaging for this operator.
The estimate includes the time for the number of local and remote messages and
the amount of data sent.
An estimate of the number of seconds to wait for an event to happen. The estimate
includes the amount of time to open a table or start an ESP process.
The number of times the operator will be executed. Usually, this value is 1, but it
can be greater when you have, for example, an inner scan of a nested-loop join.
OPERATOR
------------------------------
1
FILE_SCAN
2
PARTITION_ACCESS
3
SPLIT_TOP
4
ROOT
OPERATOR_COST
---------------
9.1667249E-003
0.0000000E+000
0.0000000E+000
1.1152706E-006
EXPLAIN Function
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