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AWR

AWR Warehouse

I just noticed last week that there is a new patch for Enterprise Manager and it is enabling AWR Warehouse feature. There is a note ID 1901202.1 which describe bundle patch for OEM 12c release 4.

Today I had a chance to install it in my lab and now I can start testing new OEM feature.
There is some documentation here and on Kellyn's blog.

Averages

Recently while observing AWR reports, I’ve seen a very good example of how average value hides important pattern.

Here is a Workload Comparison section from an AWR diff report (generated with $ORACLE_HOME/rdbms/admin/awrddrpt.sql):

Readable Code for Modify_Snapshot_Settings

It annoyed me slightly that when I googled modify_snapshot_settings just now and all of the examples used huge numbers for the retention with (at best) a brief comment saying what the number meant. Here is a better example with slightly more readable code. Hope a few people down the road cut-and-paste from this article instead and the world gets a few more lines of readable code as a result. :)

On a side note, let me re-iterate the importance of increasing the AWR retention defaults. There are a few opinions about the perfect settings but everyone agrees that the defaults are a “lowest common denominator” suitable for demos on laptops but never for production servers. The values below are what I’m currently using.

Readable Code for Modify_Snapshot_Settings

It annoyed me slightly that when I googled modify_snapshot_settings just now and all of the examples used huge numbers for the retention with (at best) a brief comment saying what the number meant. Here is a better example with slightly more readable code. Hope a few people down the road cut-and-paste from this article instead and the world gets a few more lines of readable code as a result. :)

On a side note, let me re-iterate the importance of increasing the AWR retention defaults. There are a few opinions about the perfect settings but everyone agrees that the defaults are a “lowest common denominator” suitable for demos on laptops but never for production servers. The values below are what I’m currently using.

Readable Code for Modify_Snapshot_Settings

It annoyed me slightly that when I googled modify_snapshot_settings just now and all of the examples used huge numbers for the retention with (at best) a brief comment saying what the number meant. Here is a better example with slightly more readable code. Hope a few people down the road cut-and-paste from this article instead and the world gets a few more lines of readable code as a result. :)

On a side note, let me re-iterate the importance of increasing the AWR retention defaults. There are a few opinions about the perfect settings but everyone agrees that the defaults are a “lowest common denominator” suitable for demos on laptops but never for production servers. The values below are what I’m currently using.

v$sqlstats

Sometimes you find bugs on MOS (Metalink, OCIS, whatever) that make you feel positively ill. I’ve just been on a customer site where (in passing) they mentioned that one of their historic queries avainst v$sqlstats now tool just over one second (CPU) in 11.2.0.3 when it had previously taken about 200ms on 10.2.0.4***. After a little checking it seemed likely that the change was possibly related to the fact that they had increased the size of the SGA significantly, allowing for a much larger shared pool and library cache; however there have been numerous code changes in the shared pool area on the route from 10g to 11g, so I decided to check MOS to see if anyone else had seen a similar problem. I found this:

Bug 13550185 : QUERIES ON V$SQLSTATS MAY CAUSE CRASH OR HANG

Version 11.2.0.3

Fixed in 12.1

Load profile

I like Load profile section of Statspack or AWR reports (who doesn’t). It’s short and gives a brief understanding of what kind of work a database does. But what if you don’t have an access to Statspack or AWR but still want to see something similar? It’s possible to use V$SYSMETRIC to get this numbers for last 60 or 15 seconds. I wanted to write a script to do this for a long time. Here it is.

Oracle database features wish list – 2 (V$SQL_UNSHARED_CURSOR)

It’s been too long from a previous wish for Oracle. While reading a MOS updated articles (in a new HTML interface which looks nice, much better than flash-based introduction) I’ve seen this document that made me write this blog post.

RuOUG in Saint Petersburg

On February 10th I was in Saint Petersburg on a seminar organized by Russian Oracle User Group. Actually, it was mostly prepared by company called Devexperts. Seminar took place in their office, with most presentations done by their people.

11.2 New views

It looks like Laimutis Nedzinskas has spent some time producing  a list of new views, and changes to existing views, for trouble-shooting specialists. The lists cover the dynamic performance views and the AWR history views, and the differences between 10.2 and 11.2. The lists include, where relevant, convenient hyperlinks to the view definitions in the online copy of  the 11g Server Reference manual.

I haven’t checked the lists in detail, but I can see myself  taking advantage of his efforts from time to time: