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SQL Optimizer for DB2 LUW 4.4.1 - Installation Guide

Statistics Page

ClosedView the Summary tab

The Summary tab in the SQL Optimizer window displays the Run Time information and the cost estimates from various perspectives.

Run Time Pane

The Run Time pane displays the run time statistics for retrieving all records and for retrieving the first record.

Cost Estimates

Cost statistics shown on the Summary tab are estimated cumulative costs across all operations used in the access plan.

Item

Description

Buffers

The estimated cumulative number of logical read requests for data pages that have gone through the buffer pool. This value is expressed in 4KB page units.

Communication

The estimated cumulative communication cost of executing the access plan up to and including the operation specified in the selected step. This value is expressed in TCP / IP frame units.

CPU

The estimated cumulative number of CPU instructions required to execute the access plan up to and including the operation specified in the selected step.

First row

The estimated cumulative cost of fetching the first row of data for the access plan up to and including the operation specified in the selected step. This statistic is expressed in timeron units.

First row comm .

The estimated cumulative communication cost of fetching the first row of data for the plan up to and including the operation specified in the selected step. This statistic is expressed in TCP / IP frame units.

I/O

The estimated total number of I/Os required for the access plan, up to and including the operation specified in the selected step. This value is expressed in units of 4KB pages.

Next row CPU

The estimated cumulative number of CPU instructions required to fetch the second row of data for the plan up to and including the operation specified in the selected step.

Next row I/O

The estimated cumulative number of I/Os required to fetch the second row of data for the plan up to and including the operation specified in the selected step. This statistic is expressed in timeron units.

Next row total

The estimated cumulative cost of fetching the second row of data up to and including the operation specified in the selected step. This statistic is expressed in timeron units.

Charts

The statistics from the grid are grouped together and displayed in charts.

To select how many records are displayed in the charts

Select the number from the Number of Alternatives list.

To select which statistic to use to select the records

Select the statistic from the By list.

To select the top or the bottom range of the statistic

Select Asc (Ascending) or Desc (Descending) from the Order option.

Display or Hide Panes

Use the pane-control buttons to reorganize the panes:

To display the statistics and charts

Click Chart and Statistics .

To display only the charts 

Click Chart Only.

To display only the statistics

Click Statistics Only .

 

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