Category Archives: Uncategorized

I decided to read the entire Oracle 12c Concepts manual.  It’s kind of overkill to read the entire manual if you just want to learn the new 12c features but it has been a long time since I’ve read the … Continue reading →

Here is the sqlplus scripting I use to check whether row chaining is degrading a query’s performance: VARIABLE monitored_sid number; begin SELECT sid into :monitored_sid from v$session where audsid=USERENV(‘SESSIONID’); end; / select b.value “table fetch continued rows” from V$SESSTAT b … Continue reading →

Today is the second anniversary of my first post on this blog. Some time ago I played with a free blog that came with a yahoo email account that my wife and I share but didn’t get very far with … Continue reading →

I’m trying to get up to speed on 12c, especially the multitentant features.  So, I decided to read the sections of the manuals that related to using multitentant.  Here is the name of the manual I was looking at: Oracle® … Continue reading →

Saw this blog post about how Cary Millsap learned about Oracle performance tuning and I thought it was interesting: http://carymillsap.blogspot.com/2014/02/how-did-you-learn-so-much-stuff-about.html It is interesting because I’ve learned so much from Cary Millsap and Jeff Holt’s book and it is cool to … Continue reading →

In an earlier post about how query high compression eliminated row chaining in tables with more than 255 columns I got question about whether updates to tables with more than 255 columns and query high compression ran slower with this … Continue reading →

I was on call again last week and again had to do a database recovery using RMAN.  I thought I might as well document some lessons learned even though it went quite smoothly. First, here are the steps I took.  … Continue reading →

We appear to be hitting this bug on our production Exadata RAC system: Bug 14383007 – Sort runs out of temp space in RAC even when temp space is available One particular job errors out with ORA-01652 errors on the … Continue reading →

I’ve been having issues for a long time now with an Exadata RAC database that has user reports experiencing library cache lock waits.  The challenge is to figure out what is holding the library cache locks that the queries are … Continue reading →

I wanted to find out if queries against a particular table were experiencing parse time during the week.  We had previously seen issues where queries on the table would be stuck parsing for tens of minutes before they started actually … Continue reading →