Press Coverage at The Register: Click here.
This blog post offers proof that you can trigger In-Memory Column Store feature usage with the default INMEMORY_* parameter settings. These parameters are documented as the approach to ensure In-Memory functionality is not used inadvertently–or at least they are documented as the “enabling” parameters.
Update: Oracle Acknowledges Software Defect
During the development of this study, Oracle’s Product Manager in charge of the In-Memory feature has cited Bug #19308780 as it relates to my findings. I need to point out, however, that it wasn’t until this blog installment that the defective functionality was acknowledged as a bug. Further, the bug being cited is not visible to customers so there is no closure. How can one have closure without knowing what, specifically, is acknowledged as defective?
Index of Related Posts
Other Blog Updates
Please note, blog updates are listed at the end of the article.
What Really Matters?
This is a post about enabling versus using the Oracle Database 12c Release 188.8.131.52 In-Memory Column Store feature which is a part of the separately licensed Database In-Memory Option of 12c. While reading this please be mindful that in this situation all that really matters is what actions on your part effect the internal tables that track feature usage.
Make Software, Not Enemies–And Certainly Not War
There is a huge kerfuffle regarding the separately licensed In-Memory Column Store feature in Oracle Database 12c Release 184.108.40.206–specifically how the feature is enabled and what triggers usage of the feature.
I pointed out a) the fact that the feature is enabled by default and b) the feature is easily accidentally used. I did that in Part I and Part II in my series on the matter. In Part III I shared how the issue has lead to industry journalists quoting–and then removing–said quotes. I’ve endured an ungodly amount of shameful backlash even from some friends on the Oaktable Network list as they asserted I was making a mountain out of a mole hill (that was a euphemistic way of saying they all but accused me of misleading my readers). Emotion and high-technology are like watery oil.
About the only thing that hasn’t happened is for anyone to apologize for being totally wrong in their blind-faith rooted feelings about this issue. What did he say? Please read on.
From the start I pointed out that the INMEMORY_QUERY feature is enabled by default–and that it is conceivable that someone could use it accidentally. The back lash from that was along the lines of how many parameters and what user actions (e.g., database reboot) are needed for that to be a reality. Maria Colgan–who is Oracle’ s PM for the In-Memory Column Store feature–tweeted that I’m confusing people when announcing her blog post on the fact that In-Memory Column Store usage is controlled not by INMEMORY_QUERY but instead INMEMORY_SIZE. Allow me to add special emphasis to this point. In a blog post on oracle.com, Oracle’s PM for this Oracle database feature explicitly states that INMEMORY_SIZE must be changed from the default to use the feature.
If I were to show you everyone else was wrong and I was right, would you think less of me? Please, don’t let it make you feel less of them. We’re just people trying to wade through the confusion.
The Truth On The Matter
Here is the truth and I’ll prove it in a screen shot to follow:
- INMEMORY_QUERY is enabled by default. If it is set you can trigger feature usage–full stop.
- INMEMORY_SIZE is zero by default. Remember this is the supposedly ueber-powerful setting that precludes usage of the feature and not, in fact, the more top-level-sounding INMEMORY_QUERY parameter.
In the following screenshot I’ll show that INMEMORY_QUERY is at the default setting of ENABLE and INMEMORY_SIZE is at the default setting of zero. I prove first there is no prior feature usage. I then issue a CREATE TABLE statement specifying INMEMORY. Remember, the feature-blocking INMEMORY_SIZE parameter is zero. If “they” are right I shouldn’t be able to trigger In-Memory Column Store feature usage, right? Observe–or better yet, try this in your own lab:
So ENABLED Means ENABLED? Really? Imagine That.
So I proved my point which is any instance with the default initialization parameters can trigger feature usage. I also proved that the words in the following three screenshots are factually incorrect:
Screenshot of blog post on Oracle.com:
Screenshot of email to Oracle-L Email list:
I didn’t want to make a mountain out of this mole hill. It’s just a bug. I don’t expect apologies. That would be too human–almost as human as being completely wrong while wrongly clinging to one’s wrongness because others are equally, well, wrong on the matter.
BLOG UPDATE 2014.07.31: Click here to view an article on The Register regarding Oracle Database In-Memory feature usage.
BLOG UPDATE 2014.07.30: Oracle’s Maria Colgan has a comment thread on her blog on the In-Memory Column Store feature. In the thread a reader reports precisely the same bug behavior you will see in my proof below. Maria’s comment is that feature usage is tracked in spite of the supposed disabling feature INMEMORY_SIZE set to the default value. While this agrees with what I already knew about this feature it is in my opinion not sufficient to speak of a bug of such consequence without citing the bug number. Furthermore, such a bug must be visible to users with support contracts. Click here for a screenshot of the Oracle blog. In case Oracle changes their mind on such an apparently sensitive topic I uploaded the blog to the Wayback Machine here.
BLOG UPDATE 2014.07.29: Oracle’s Maria Colgan issued a tweet stating “What u found in you 3rd blog is a bug […] Bug 19308780.” Click here for a screenshot of the tweet. Also, click here for a Wayback Machine (web.archive.org) copy of the tweet.