I didn’t have a lot of time to blog during OOW16, so here is the summary of the last 4 days here. On the sessions side I didn’t go to a lot of them (as expected). I managed to miss my friends sessions (Zohar Elkayam and Ami Aharonivich) I did go to an ODA hands … Continue reading OOW16

Flashback database – dont forget the standby

Today an  application team had a problem with a production system and they wanted the database restored to a point a couple of days ago. It is a configuration management system and they figured they could lose any changes . Their call.

I did all the good things

  • Checked we had a change in place
  • Blacked out primary and standby in OEM
  • Checked flashback was on  –
select flashback_on from v$database;

Read Only Users and Database Performance

One of the questions we see being asked reasonably frequently is how to allow read only access to someone who wants to view database performance issues, using tools such as Real Time ADDM, ASH Analytics and so on. This is generally asked for someone like an application developer, who can use this information to identify performance issues in Production and then fix the root cause in their Development environments.

Well, that’s a reasonable question to (more...)

Mumbai version 3.1.1 available

Yes, it is still alive.🙂 Version 3.1.1 of Mumbai is available for download.

Mumbai served me well over the last months, so there were no updates for quite some time. However, it’s time to do at least some compatibilty fixes, especially in regards to 12c.

So here is the first shot which fixes some of the major compatibilty problems. I expect that there are more things to fix (and extend) regarding 12c and RAC (more...)

How to reinstate the old Primary as a Standby after Failover in #Oracle

You have done a failover to your Standby database so it becomes the new Primary. It may be possible to convert the old Primary into a Standby database now instead of having to do a time consuming duplicate again. The old Primary must have been running in flashback mode before the failover. The playground:

DGMGRL> show configuration;

Configuration - myconf

  Protection Mode: MaxAvailability
  prima - Primary database
    physt - Physical standby database

Fast-Start Failover:  (more...)

Approximate Query Processing in 12c Release 2

Approximate Query Processing appears to be a major feature of Oracle Database 12c Release 2 SQL. In 12cR1 patchset 2 (, we saw one approximate query function appear – APPROX_COUNT_DISTINCT to use instead of COUNT(DISTINCT). In 12.2 there are several APPROX functions introduced:   APPROX_COUNT_DISTINCT_DETAIL APPROX_COUNT_DISTINCT_AGG TO_APPROX_COUNT_DISTINCT APPROX_MEDIAN APPROX_PERCENTILE APPROX_PERCENTILE_DETAIL APPROX_PERCENTILE_AGG TO_APPROX_PERCENTILE According to Oracle […]

Community : Discussing the Meetup Format

I spent a bit of time with Liron Amitzi today brainstorming ideas about user group meetups and putting him in touch with a potential sponsor.

Since his move to Vancouver, Liron’s been involved with the user group there and he was asking for ideas about how to help promote it. I don’t claim to know much about this stuff, but I do see what others like PythianOracle Midlands and RedStackTech (#ClubOracle) have done (more...)

Oracle OpenWorld 2016 : Tuesday – Day 2

Day 2 started a little late for me. I was up early, but I logged in to work and had to do a few things. Once I had got through that I headed down to the conference…

On the way there I bumped into Ronald Bradford and we hit the exhibition hall together. We stopped by the SolarWinds stand and noticed a “Deploy Faster” sticker. Part of the promotion for the Girls Who Code Foundation. If you see one, take (more...)

Oracle Open World

My latest Oracle Press "Oracle Database Cloud Cookbook" being sold at Oracle Open World this week. Grab a copy.

ERROR: SPFile in diskgroup does not match the specified spfile

Just a stupid error. Posting it so that someone else googling for the same thing can get a clue.

An ASM instance running with default parameters (no pfile, no spfile). Updated spfile for the instance with asmcmd spset command and bounced crs. After reboot also, it still wasn’t using spfile. Got puzzled and checked GPnP settings again. All looked good. Then in alert log came across this

ERROR: SPFile in diskgroup <> does not match  (more...)

Cloud First : What does it mean to me?

cloudThe announcement that several Oracle products will be released “Cloud First” from now on has been an interesting talking point for many of us. I think I first heard this message at last years OOW, but I can’t remember if it was public, or in a meeting covered by an NDA. There have been public statements about this since then, but at OOW16 we have the first example that directly affect me!

Oracle Database 12c Release (more...)

Offline analysis of HDFS metadata


HDFS is part of the core Hadoop ecosystem and serves as a storage layer for the Hadoop computational frameworks like Spark, MapReduce. Like other distributed file systems, HDFS is based on an architecture where namespace is decoupled from the data. The namespace contains the file system metadata which is maintained by dedicated server called namenode and the data itself resides on other servers called datanodes.

This blogpost is about dumping HDFS metadata into Impala/Hive table (more...)

Why Bother

This note comes to you prompted by “Noons” in a recent twitter exchange

In response to a complaint by Lukas Eder about having to educate people in 2016 that there is no (performance) difference between count(*) and count(1), Nuno  asked me to blog about my claim that this non-difference is a good educational example on at least three different counts.

One thing I won’t count in the list of three is an actual demonstration (more...)

Oracle OpenWorld 2016 : Monday – Day 1

I’ve been away from home for over a week and we’ve finally got to Day 1 of the conference… 🙂

After not feeling too great last night I skipped the bay swim. I headed down to the conference and my first stop was the AppsLab Internet of Things (IoT) Workshop. With some help from Mark Vilrokx, I have now joined the world of the cool and hip. During the workshop you get a little Arduino (more...)

Some Exciting Customer Presentations!

While I always enjoy getting in front of customers to present on some new and really cool functionality in Enterprise Manager Cloud Control, it’s even better to be in the audience listening to actual customers doing just that!  There are a couple of those presentations coming up on Thursday this week at OOW.  Unfortunately I can’t be there to listen in, but if you’re interested in learning how to provide scalable and flexible patching solutions, (more...)

New ORAchk & EXAchk Versions Released

New ORAchk & EXAchk v12. release is out now with so many new features. Its easy to use and upgrade.

Below is the blog entry about the new release and features by RAC Assurance Development team at Oracle:


Video Tutorial: XPLAN_ASH Active Session History – Part 11

The next part of the video tutorial explaining the XPLAN_ASH Active Session History functionality continuing the actual walk-through of the script output.

More parts to follow.

Oracle ACED Briefing and Open World

My first Oracle HQ visit was for the Oracle ACE Director briefing. Had two good days at the HQ. The briefing started with a super cool session by Thomas Kurian (President, Product Development). He was ready to answer any and all questions we had. Learned a lot about the Oracle cloud products that are on […]

Statement-level PARALLEL Hint

From version 11.2 onward, the PARALLEL hint supports two syntaxes: object-level and statement-level. The object-level syntax, which is the only one available up to version 11.1, overrides the DOP associated to a tables. The statement-level syntax can not only override the PARALLEL_DEGREE_POLICY initialization parameter at the SQL statement level, but also force the utilization of parallel processing.

The statement-level PARALLEL hint supports the following values:

  • PARALLEL(DEFAULT) forces the default DOP. Note that the (more...)

Stats Collection Time Anomaly

Johnathan Lewis (@JLOracle) recently published a short post about Stats Collection Time, talking about the table dba_optstat_operation (and dba_optstat_operation_tasks ), which reminded me about (what I regard as) an anomaly in the output in the NOTES columns in Oracle 12C.

I won’t repeat why it’s useful to check these tables as Johnathans note and @MDWidlakes’s comment here should give you all you need to know.

The DBA_OPTSTAT_OPERATION.NOTES column contains the (more...)