The Explain tab displays detailed information about how the statements are executed and provides estimates of the resource requirements for the statements.
Column
|
Description
|
StmtText | For rows that are not of type PLAN_ROW, this column contains the text of the Transact-SQL statement. For rows of type PLAN_ROW, this column contains a description of the operation. This column contains the physical operator and may optionally also contain the logical operator. This column may also be followed by a description that is determined by the physical operator. |
StmtId | Number of the statement in the current batch. |
NodeId | ID of the node in the current query. |
Parent | Node ID of the parent step. |
PhysicalOp | Physical implementation algorithm for the node. For rows of type PLAN_ROWS only. |
LogicalOp | Relational algebraic operator this node represents. For rows of type PLAN_ROWS only. |
Argument |
Provides supplemental information about the operation being performed. The contents of this column depend on the physical operator. |
DefinedValues |
Contains a comma-separated list of values introduced by this operator. These values may be computed expressions which were present in the current query (for example, in the SELECT list or WHERE clause), or internal values introduced by the query processor in order to process this query. These defined values may then be referenced elsewhere within this query. For rows of type PLAN_ROWS only. |
EstimateRows |
Estimated number of rows of output produced by this operator. For rows of type PLAN_ROWS only. |
EstimateIO |
Estimated I/O cost* for this operator. For rows of type PLAN_ROWS only. |
EstimateCPU |
Estimated CPU cost* for this operator. For rows of type PLAN_ROWS only. |
AvgRowSize |
Estimated average row size (in bytes) of the row being passed through this operator. |
TotalSubtreeCost |
Estimated (cumulative) cost* of this operation and all child operations. |
OutputList |
Contains a comma-separated list of columns being projected by the current operation. |
Warnings |
Contains a comma-separated list of warning messages relating to the current operation. Warning messages may include the string "NO STATS:()" with a list of columns. This warning message means that the query optimizer attempted to make a decision based on the statistics for this column, but none were available. Consequently, the query optimizer had to make a guess, which may have resulted in the selection of an inefficient query plan. |
Type |
Node type. For the parent node of each query, this is the Transact-SQL statement type (for example, SELECT, INSERT, EXECUTE, and so on). For subnodes representing execution plans, the type is PLAN_ROW. |
Parallel |
0 = Operator is not running in parallel. |
EstimateExecutions |
Estimated number of times this operator will be executed while running the current query. |
* Cost units are based on an internal measurement of time, not wall-clock time. They are used for determining the relative cost of a plan in comparison to other plans.