ORA-00600 encountered while performing DBMS_STATS on table with too many columns

My Oracle Support document "ORA-00600 [kkqtutlAddSelItem] when Running DBMS_STATS on Table with Large Number of Columns" from article ID 1619803.1 reminds me a lot of a previous article where I found out about an ORA-00600 error when you try to select from too many tables at once!  It seems like you can run into these issues at "random" times when artificial limits are imposed within the Oracle database internals so be aware of these issues!

Weekend Learning: 12c Invisible Columns

Sure, I mentioned that Tom Kyte shared something about invisible columns but I do not think that I read the post he linked to which did go a bit deeper into the subject.  I bring this up, because I found a pretty good article that walks us through several scenarios around making columns invisible in 12c.

Do you know if a column can be selected if it is marked as invisible?  Are there any pitfalls you need to avoid when changing this property of the column?  If you aren't sure of the answer to these questions, go visit the article from Rajesh and learn something new this weekend!

What's the difference in a column?

This blog is filled with the times I'm just so brilliant, but this is not one of those times.  In our due-diligence in verifying all our items, objects, and processes will stand up to being upgraded by R12 an analyst started asking us some questions about an alert which just so happens to be one I created.  The statement was being made that "it does not pull up anything" which was curious to me, since I usually don't send alerts out unless I can test them successfully (often many many times) before putting my team on them.  Sure enough, I went back to see that I DID test the alert and it DID show information so now I'm really curious and digging into the statements being made in relation to actual_start_time being selected as the criteria for the alert.

Seems innocent enough right?  I had wanted to find out when a Journal Import ended within the first hour of it being in a non-normal status (Cancelled, Terminated, Error, you get the idea) but in fact that isn't what I asked the alert to do.  Because I used actual_start_time, and not actual_completion_time, I was asking the alert to tell me if a Journal Import ended in a non-normal state only if it started within the past hour.  How about that huh?  So I looked back in the history of when the alert should have come out, and sure enough there was a Journal Import that started at 8 AM and didn't end abnormally until after 10 AM so when the alert ran this wasn't picked up.  A good lesson learned that even with good intentions, you can do something completely wrong, and not find out about it until too late.