Sunday, December 21, 2014

New Version Of XPLAN_ASH Utility

A new version 4.2 of the XPLAN_ASH utility is available for download.

As usual the latest version can be downloaded here.

There were no too significant changes in this release, mainly some new sections related to I/O figures were added.

One thing to note is that some of the sections in recent releases may require a linesize larger than 700, so the script's settings have been changed to 800. If you use corresponding settings for CMD.EXE under Windows for example you might have to adjust accordingly to prevent ugly line wrapping.

Here are the notes from the change log:

- New sections "Concurrent activity I/O Summary based on ASH" and "Concurrent activity I/O Summary per Instance based on ASH" to see the I/O activity summary for concurrent activity

- Many averages and medians now also have accompanying minimum and maximum values shown. This isn't as good as having histograms but gives a better idea of the range of values, and how potentially outliers influence the average and deserve further investigations

- Bug fixed: When using MONITOR as source for searching for the most recent SQL_ID executed by a given SID due to some filtering on date no SQL_ID was found. This is now fixed

- Bug fixed: In RAC GV$ASH_INFO should be used to determine available samples

- The "Parallel Execution Skew ASH" indicator is now weighted - so far any activity level per plan line and sample below the actual DOP counted as one, and the same if the activity level was above
The sum of the "ones" was then set relative to the total number of samples the plan line was active to determine the "skewness" indicator

Now the actual difference between the activity level and the actual DOP is calculated and compared to the number of total samples active times the actual DOP
This should give a better picture of the actual impact the skew has on the overall execution

- Most queries now use a NO_STATEMENT_QUEUING hint for environments where AUTO DOP is enabled and the XPLAN_ASH queries could get queued otherwise

- The physical I/O bytes on execution plan line level taken from "Real-Time SQL Monitoring" has now the more appropriate heading "ReadB" and "WriteB", I never liked the former misleading "Reads"/"Writes" heading

1 comment:

Martin Preiss said...

ah, I see, it's christmas again...