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aud$ and ASSM – a good combination

We had a 8 node RAC cluster that was showing evidence of connections timing out. The following AWR report segments indicates a high level of login activity and blocking on the AUD$ table and segments.


The ‘rfs writes’ event on a DataGuard standby database

It is well known that poor performance on the standby server of a DataGuard pair can affect the performance of the primary database. This post shows an example and how to use the view GV$EVENT_HISTOGRAM to track down an issue.

The databases were on HPUX. I had been seeing alerts from OEM to state that the standby was seeing lag_apply delays when applying redo to standby. Looking at the primary database alert log I could see the entries

Serious BUG alert – RMAN Duplicate overwrites datafiles at original location

Please be aware of the serious bug identified with RMAN duplicate database on the same node with versions and

Bug 13498382  ORA-1122 ORA-1208 RMAN Duplicate overwrites datafiles at original location despite db_create_file_dest

This note gives a brief overview of bug 13498382.
The content was last updated on: 07-FEB-2014
Click here for details of each of the sections below.

Invisible Indexes – a real world example and a bit of LogMiner

We had a requirement to perform a one-off update on a table of around 1.2M rows. There were 11K statements similar to the one below, with varying values and predicates updating a variety of rows from 20 to 500. The potential elapsed time was around 44 hours due to the volume of full table scans involved.

The obvious thing to do was to create an index but this was production and it was urgent so no time to go through the full route to live test cycle.

Oracle Restart – going , going , gone?

Oracle restart is an 11GR2 feature which ensures that all services on a standalone installation start up in the correct order. As such it seems to work well. One bugbear I have with it is that it changes the order of entries in the /etc/oratab file. Personally I like my oratab to be ordered in terms of database (most used first), ASM, then agents. In that way when I logon to a box and it automatically sets the SID it picks up the first entry which is commonly the database I want to work with.

2014 technology ambitions – just the two

As this the traditional time to layout resolutions for the year here are my 2 database related ones.

To understand more about some of the newer technologies and to advance my use of APEX as a means of providing reporting information around the systems and people I manage.

2013 blog activity

At the end of the year WordPress produce a brief analysis of activity on my blog

The Louvre Museum has 8.5 million visitors per year. This blog was viewed about 160,000 times in 2013. If it were an exhibit at the Louvre Museum, it would take about 7 days for that many people to see it.

In 2013, there were 25 new posts, growing the total archive of this blog to 176 posts. There were 32 pictures uploaded, taking up a total of 5 MB. That’s about 3 pictures per month.

Merry Xmas and a project goes live

I hope all my readers have a Merry Xmas and a Happy 2014.

My company has finally delivered an online delivery solution (we are a major food retailer in the UK  for anyone who does not recognise the branding). It is always nice to see a major project go-live and this is one that has caused some pressure in recent months.

I do think that whilst  the courgettes comment is funny and relevant to the emphasis we put on fresh food it might seem a bit stale (no pun intended) after a while. new features and a OPTIMIZER_DYNAMIC_SAMPLING change

As of 27th August  2013,, the final release of 11GR2 was made available – a new features document is available . I will give a quick bullet list of the new features and then discuss one very important one that is not mentioned.

UKOUG – Tech13 – day 3 review

Another busy day at the Manchester Central complex. An early start with Martin Nash talking about RAC connectivity issues and bugettes. Very interesting but I don’t think my brain was fully in gear at 08:30 after a big hotel breakfast.

Straight into another two-man CERN presentation on Lost Writes. The first half was  about a scenario they had seen where an index has lost some data and frankly there was no explanation for what caused it to happen. However the second part was around how you might deal with the scenario and that was very good and gave a lot of food for thought.

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