There was a question in the twitter-sphere about whether using sequences (sequence.NEXTVAL) in your select query’s projection list would somehow disable smart scans happening?
The answer is no, sequence use with smart scans works just fine. The smart scan offloading applies to data retrieval row sources (and filtering) only and nothing else. So, what you have in the query’s projection list (the sequence use for example), does not directly affect the smart scan decision. Just like any other operations like sorting, grouping etc, do not have anything to do with smart scans and don’t disable their use. Smart scans are only related to data retrieval and any other operations do not affect them.
Prompted by a recent interview I wanted to perform a little test with RMAN, and incrementally updated backups. I created a 18.104.22.168.5 database on my Linux (OEL 5.5) test system and refreshed my understanding of this most useful rman feature (which is for another post).
So after I was happy with the working of the incrementally updated image copies I decided to see if I could restore my database with those. Time to use “drop database”, which removes spfile, data files, temp files and the control files. Tabula rasa!
But it didn’t matter I thought: I have controlfile/spfile autobackups and fully recovered image copies plus all the archived logs in the FRA. What could possibly go wrong? Well it took me 30 minutes to get the database back.
Thanks everyone who attended yesterday's webinar at AllThingsOracle.com.
I hope the technical difficulties with my new mic (which of course work flawlessly during several test runs) weren't too severe so that you could still understand what I said.
As usual when I do presentations in English it took me far too long so probably some of you missed the end of the session. If you did you may want to check the webinar recording once available at the webinar archive at AllThingsOracle.com, because we had a very good and extensive Q+A session with excellent questions asked.
Thanks again to AllThingsOracle.com and James Murtagh for hosting the event.
This post is long overdue, and it’s as much a reminder to myself as it is a post for you to find when scratching your head.
Here’s the situation: Oracle Restart on an Oracle Enterprise Linux 5.5 system with ASMLib in use. I have installed 22.214.171.124 plus the latest PSU to bring database and Grid Infrastructure to 126.96.36.199.5-so far so good. I have used the non-GUI approach and everything seemed ok until I tried to create a database for some benchmarking. Here’s the surprising output:
Well apparently you can teach an old dog new tricks. I recently sent the following email to Enkitec’s internal techie email list:
Begin forwarded message:
Have you ever tried to decipher a really ugly, unformatted SQL statement that someone gave you or you pulled out of one the database views or an AWR report? Tim Fox turned me on to the SQL formatting capability of SQL Developer a few weeks ago (actually Brian Hill found it first and showed Tim). It is awesome! It’s a little unintuitive to use though. Here’s how I use it.
I’m very keen on the 11g extended stats feature, but I’ve just discovered a critical weakness in one of the implementation details that could lead to some surprising instability in execution plans. It’s a combination of “column group” statistics and “out of range” predicates. Let’s start with some sample data. (Note: I was running this test on 188.8.131.52):
create table t1 as with generator as ( select --+ materialize rownum id from dual connect by level <= 10000 ) select mod(rownum,100) col1, mod(rownum,10) col2 from generator v1, generator v2 where rownum <= 50000 ; begin dbms_stats.gather_table_stats( ownname => user, tabname =>'T1', method_opt => 'for all columns size 1' ); end; /
I’ve just tried the alpha of Fedora 17 to see if the GNOME 3 software rendering works and it did. You may recall, since updating my graphics card I’ve been forced to use the fallback mode on Fedora 16. I’m quite keen to move back to proper GNOME 3, which looks like it will be possible when F17 is released.
On a VM it seems a little on the slow side, so I hope this isn’t an indication that it will be annoying on my desktop. I guess time will tell. Fingers crossed though.
Ok fellow internals geeks, tomorrow’s going to be another 1-hour hacking session (which will probably take 2 hours) with me. It’s about how Oracle parameters work and all the different types of them too. See the registration link for more info:
Date: 12 april 2012
Time: 9am Pacific (see in other timezones here)
April 11, 2012 I recently received an interesting request for assistance from an ERP email mailing list. The author of the email wanted to reproduce a canned report found in the ERP package so that the information could be published on a Microsoft Sharepoint system. The author of the email is using SQL Server for [...]
As discussed previously, one of the nice features of an IOT Secondary Index is that it contains the mandatory Primary Key of the IOT, which is always maintained and can be used to access the necessary rows of the IOT regardless of row movement within the IOT itself. This can also be beneficial if only the PK [...]