Category Archives: Indexes

My Collaborate IOUG 2015 Abstract

I will be presenting DBA 3.0 or “How to Become a Real-World Exadata DBA” at Collaborate 2015 – IOUG’s annual user conference – from April 12th to 16th at the Mandalay Bay Resort and Casino in Las Vegas. I submitted this as my abstract:

“DBA resources are more scarce than ever before and it can be very difficult to allocate time on anything but keeping the lights on – even when an organization has made a (substantial) hardware investment in Exadata.

However, if Exadata is treated like any other Oracle database, the promised “extreme performance” will likely be very underwhelming to developers, users and managers and can become unwieldy for DBAs to support.

On the other hand, when an organization configures and supports Exadata properly, they can realize exponential performance improvements in key IT infrastructure, can facilitate better business decisions and may actually reduce infrastructure costs.

The customer has bought a sports car – but might not realize that they haven’t taken it out of second gear (yet).

I will talk about the evolution of Exadata and then get into the “nuts and bolts” of how to support a high-performance Exadata environment as a Production DBA.

I will discuss how to get performance improvements of up to 20x, what NOT to do as an Exadata DBA and how Exadata can become the foundation of your organization’s high-performance enterprise infrastructure.”

I hope to see you in Las Vegas!

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DBMS_REPAIR and Unfinished Online Index Rebuilds

I have, seriously, no clue how I haven’t seen this before today, but in case you haven’t either, this is how to use DBMS_REPAIR to clean up after unfinished online index rebuilds.

I know there are opposing schools of thought with rebuilding or reorganizing indexes, but, for the sake of argument, let’s say that I decided to perform an online rebuild of the MARKTAB_UX_IDX index in the MARKAPP schema this afternoon.

It doesn’t really matter why – Segment Advisor jumping up and down with its hair on fire, a shot-in-the-dark request from an application vendor or a DBA trying to extending a datafile and avoiding adding to the “tab” running with the storage guys – let’s just assume I issue this command:

ALTER INDEX markapp.marktab_uk_idx REBUILD ONLINE TABLESPACE markapp_i01;

I kick it off, but nothing appears to be happening. After a while, I check for blocking locks and notice that a user is running something which is holding an exclusive lock on the MARKAPP.MARKTAB table – something to add to my list of things to investigate – thus preventing me from starting the index rebuild.

After determining that user is doing something important and really can’t be persuaded to release that exclusive lock for the next hour or two, let’s say that I decide to kill my session to stop the ALTER INDEX … statement.

Again, it might not be the best decision, but bear with me.

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