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September 2014

Oracle IO wait events: db file sequential read

(the details are investigated and specific to Oracle’s database implementation on Linux x86_64)

Exadata IO: This event is not used with Exadata storage, ‘cell single block physical read’ is used instead.
Parameters:
p1: file#
p2: block#
p3: blocks

Despite p3 listing the number of blocks, I haven’t seen a db file sequential read event that read more than one block ever. Of course this could change in a newer release.

FARNHAM for US Senate Campaign 4 Hashtags, 3 Key concepts

One of my friends noticed that I am trying to push forward campaign finance reform by trying to win without a TV media budget, and he asked what was my hash tag. DOH! I should have created hash tags long ago. Okay, there is still time to go viral. I’ve registered four hash tag definitions with hashtag.org, and I’ll explain them here, first with just the snapshot definitions I could get to stick without the site complaining : Stop! You’re posting too fast and then with the full story as individual blog posts. Hang in there. This is important.

Oh, and my top priority is establishing the #SAFE_DEAL.

#SAFE_DEAL

A system where the government makes sure all persons legally resident start with a base minimum income of at least the poverty level and get to retain at least 65 cents on each dollar they earn. See rsiz.wordpress.com for the details.

#WRONG_GAP and #CORRECT_GAP

WordPress 4.0

WordPress 4.0 “Benny” has been released. The download is in the usual place, but you are probably going to upgrade by clicking the auto-upgrade button.

I did 4 upgrades and all went fine. I can’t say things look that different after it, but you’ve got to keep on top of these upgrades I guess.

Cheers

Tim…

 


WordPress 4.0 was first posted on September 4, 2014 at 10:30 pm.
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RESULT_CACHE Hint in 12.1.0.2

Every new Oracle Database patch introduces not only documented features, but also undocumented ones. In this short post I would like to provide information about an enhancement of the RESULT_CACHE hint.

According the documentation, the RESULT_CACHE hint has no parameter. But, as of 12.1.0.2, at least the SNAPSHOT parameter is supported. Its purpose is to specify how much time (in seconds) after the creation the result cache entry has to expire. In other words, you can specify that a specific entry expires even though the objects is based on doesn’t change.

The following example illustrates:

Group By Bug

This just in from OTN Database Forum – a surprising little bug with “group by elimination” exclusive to 12c.


alter session set nls_date_format='dd-Mon-yyyy hh24:mi:ss';

select
       /* optimizer_features_enable('12.1.0.1')*/
       trunc (ts,'DD') ts1, sum(fieldb) fieldb
from (
  select
        ts, max(fieldb) fieldb
  from (
  select trunc(sysdate) - 1/24 ts, 1 fieldb from dual
  union all
  select trunc(sysdate) - 2/24 ts, 2 fieldb from dual
  union all
  select trunc(sysdate) - 3/24 ts, 3 fieldb from dual
  union all
  select trunc(sysdate) - 4/24 ts, 4 fieldb from dual
  union all
  select trunc(sysdate) - 5/24 ts, 5 fieldb from dual
  )
  group by ts
)
group by trunc (ts,'DD')
/

You might expect to get one row as the answer – but this is the result I got, with the execution plan pulled from memory:

EM12c and Windows OS Failover Cluster- Keep it Simple

This is going to be a “KISS”, (Keep it Simple, Silly) post.  I was offered a second Windows cluster to test on when my original one was required for QA.  It was a gracious offer, but I also found out why a cluster should be kept simple and this cluster was anything but simple.  Many times, issues are created and we’ll never see them coming until we go through the pain and the EM

5 secrets 10% of Fortune 500 use to double application development output

#222222;">#808080;">This article liberally uses sections from #0000ff;">#0000ff;">The Threat That Lies Within  by Yaniv Yehuda

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Databases receive much attention so they will not become THE risk factor of IT. Budgeting DRPs, backups, top of the line DBAs – and yet, they still pose a major threat. Why?

Teach Your Children Well

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Today’s the first day of school in my city, and the plethora of “OMG 1st day of school!” posts of Facebook and my own kids heading back in to slog through another year of fundamentals got me thinking about education. My own kids (12/daughter and 10/son) came home and went swimming since it was about 104 degrees today…the hottest day of the summer, as it were.

Who is using this index?

Or, to put it another way, I want to change or drop this index, who and what will I impact?

The Challenge 

The problem that I am going to outline is certainly not exclusive to PeopleSoft, but I am going to illustrate it with examples from PeopleSoft. I often find tables with far more indexes than are good for them.
  • The Application Designer tool makes it very easy for developers to add indexes to tables. Sometimes, too easy!
  • Sometimes, DBAs are too quick to unquestioningly follow the advice of the Oracle tuning advisor to add indexes.

Recently, I have been working on 3 different PeopleSoft Financials systems where I have found major tables with a host of indexes.

There are several concerns: