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Column Name
TNAME
CARDINALITY
OPERATOR_COST
TOTAL_COST
DETAIL_COST
DESCRIPTION
The DETAIL_COST column contains these cost factors:
Table 2-5 Cost Factors of DETAIL_COST column
CPU_TIME
IO_TIME
MSG_TIME
IDLETIME
PROBES
The following example has been edited to allow it to be displayed here (lines folded, trailing
blanks removed, and so on).
This example uses OPTIONS 'm':
>>explain options 'm' select * from region;
Data Type
CHAR(60)
REAL
REAL
REAL
VARCHAR (200)
VARCHAR (3000)
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.
Description
For operators in scan group, full name of base table,
truncated on the right if too long for column. If
correlation name differs from table name, simple
correlation name first and then table name in
parentheses.
Estimated number of rows that are returned by the
current operator. Cardinality appears as
ROWS/REQUEST in some forms of EXPLAIN output.
For the right child of a nested join, multiply the
cardinality by the number of requests to get the total
number of rows produced by this operator.
Estimated cost associated with the current operator to
execute the operator.
Estimated cost associated with the current operator to
execute the operator, including the cost of all subtrees
in the operator tree.
Cost vector of five items, which are described in detail
in the next table.
Additional information about the operator. For a
detailed look at all operators, see the Neoview Query
Guide.
EXPLAIN Statement
111
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