Database Reference
In-Depth Information
Table 10-1. ( continued )
Column
Description
Runtime Statistics*
Starts
The number of times a specific operation was executed. In some special
cases, this statistic shows the number of times a specific memory
structure was accessed (as shown later on in the “Unrelated-Combine
Operations” section).
A-Rows
The actual number of rows returned by the operation.
A-Time
The actual amount of time spent executing the operation (HH:MM:SS.FF).
I/O Statistics*
Buffers
The number of logical reads performed during the execution.
Reads
The number of physical reads performed during the execution.
Writes
The number of physical writes performed during the execution.
Memory Utilization Statistics
OMem
The estimated amount of memory (in bytes) needed for an
optimal execution.
1Mem
The estimated amount of memory (in bytes) needed for a
one-pass execution.
O/1/M
The number of times the execution was performed in optimal/one-pass/
multipass mode.
Used-Mem
The amount of memory (in bytes) used by the operation during the last
execution.
Used-Tmp
The amount of temporary space (in kilobytes) used by the operation
during the last execution. This value must be multiplied by 1,024 to be
consistent with the other memory utilization columns (for example, 32K
means 32MB).
Max-Tmp
The maximum amount of temporary space (in kilobytes) used by the
operation. This value has to be multiplied by 1,024 to be consistent with
the other memory utilization columns (for example, 32K means 32MB).
*Available only when execution statistics are enabled.
The next section shows the query block names and the object aliases:
Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------
1 - SEL$1
3 - SEL$1 / T2@SEL$1
4 - SEL$1 / T2@SEL$1
5 - SEL$1 / T1@SEL$1
 
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