Database migration with datapump 10g->12c



Finally one of our 'legacy' systems is being brought up to date after many years of languishing on oracle 9. We're so far behind that a migration route is not straightforward (at least one that runs in a reasonable timeframe) so we are left with this convoluted route (there are reasons for this but i won't go into that for now - in fact i'm just going to cover one of these sections).

So general (more...)

Upgrade to Oracle 12c, Get the Huge Trace Files for Free!

Last week we began testing a copy of our production database on Oracle 12c (12.1.0.2). This past weekend we were alerted that the disk holding our ADR diagnostic directory was near full. We noticed some pretty big (and recent) trace files there. Then it happened twice more. This last time filled the disk before we could get to it (thankfully only dev, and during the evening), meaning it filled up fast. The (more...)

So long, and thanks for all the fish

After fifteen years at the helm of Scale Abilities, I have decided it's time for the next chapter. Scale Abilities is closing down and I'm taking a job with another company. Fifteen years is a long time, especially in the technology business, and it might be a bit of a shock to those that have […]

Snap Cloning Databases on Exadata using Enterprise Manager

By Subhadeep Sengupta (Oracle)
Historically, Exadata has mostly been deployed for heavy, production workloads, leaving cheap commodity hardware and third-party storage to perform as infrastructure for Development and Testing. From the viewpoint of Enterprise Manager, we have seen customers clone production databases running on Exadata to secondary storage such as ZFS Storage Appliance or even third-party NAS or SAN for the purpose of testing. Customers mainly used RMAN (with or without Enterprise Manager) to (more...)

Oracle Management Database in Grid Infrastructure: -MGMTDB

Oracle,

Why? Why is is now mandatory to have the cluster management database as an Oracle CDB, with a PDB having the same name as the cluster? It’s not that I object to having another 1GB of memory lost to this DB, and up to 10GB of disk in the initial ASM Disk Group. It’s this:

You have called it -MGMTDB

That means I now have directories all over my Linux / Unix structure called (more...)

Oracle on 4096 (4k) sector disks don’t work (ish)

I recently came across 4K (4096 byte) sector drives. They are a fairly new thing and have come about so drives can exceed the 2TB limit imposed by having 512byte sectors. The details behind this can be found here, in much greater detail than I need to understand.

What I do understand is that Oracle doesn’t deal with 4K sectors (4Kn) very well and it shows up in a couple of ways. Don’t get me (more...)

Oracle DBAs: Producing Patches

In an Oracle DBA’s life, you’ll be regularly asked to work on applying a new patchset on a database and then you will apply it starting from the development database to the production database and this process can be quite long depending on the organization you are working for.

In an Oracle DBA’s life, you’ll be regularly asked to refresh a development database (or any environment before the production) with the production data for development, test or whatever needs. For (more...)

How to avoid boring work

For a last couple of years when I was working as an IT consultant I learned that having robust and easy access to lab when I can learn or test solution is one of critical thing. My approach to build that was changing over a years and changes in a technology itself.

In the current times I believe that "building" a lab step by step is not a most efficient way I can use my (more...)

Auditing on Physical Standby Database with XML

Turning on auditing on a physical standby database may be preferred when you want to audit the queries against the read only standby database. Obviously it's not possible to keep audit records on standby database by setting audit_trail to DB or DB_EXTENDED. Because the database is read-only and the aud$ table is just being synchronized with the primary aud$. So the DB or DB_EXTENDED setting on a

12c Downgrade

No, not really – but sometimes the optimizer gets better and gives you worse performance as a side effect when you upgrade. Here’s an example where 11.2.0.4 recognised (with a few hints) the case for a nested loop semi-join and 12c went a bit further and recognised the opportunity for doing a cunning “semi_to_inner” transformation … which just happened to do more work than the 11g plan.

Here’s a data set to (more...)

Putting Data Guard traffic on dedicated network interface

I recently had an interesting challenge to direct data guard network traffic over a dedicated network interface and not go though the main network routes. The reason was that in order to reach the remote datacenter, the dataguard traffic should be sent via WAN optimizer network, that will automatically compress and dedup all traffic (hard to believe, that there are still some places left in Europe, where internet bandwidth is extremely expensive). I know that (more...)

Focusing on Ext4 and XFS TRIM Operations – Part I.

I’ve been doing some testing that requires rather large file systems. I have an EMC XtremIO Dual X-Brick array from which I provision a 10 terabyte volume. Volumes in XtremIO are always thinly provisioned. The testing I’m doing required me to scrutinize default Linux mkfs(8) behavior for both Ext4 and XFS. This is part 1 in a short series and it is about Ext4.

Discard the Discard Option

The first thing I noticed in this (more...)

Partitioning to the rescue



One of our core 3rd party applications has some functionality where results of certain calculations are extracted once per day into customer defined tables for use by downstream systems and interfaces. These results (and there are various different calculations outputting to various different tables) are retained based on business requirements for periods of either a week, a month or sometimes up to 6 months or a year. As the retention length is passed the oldest (more...)

Log Buffer #432: A Carnival of the Vanities for DBAs

Yet again, this log buffer edition brings some rich blog posts from Oracle, SQL Server and MySQL.

Oracle:

  • Installing Oracle XE, ORDS and Apex on CentOS
  • Major Growth is Expected in the DBaaS Space. Are Your Skills Ready?
  • How to Hide Actions in OBPM 12c Workspace
  • You can configure auto refresh for ADF BC cached LOV and this works out of the box, no special coding is needed.
  • Search and Replace in Oracle SQL Developer (more...)

Announcing “SLOB Recipes”

I’ve started updating the SLOB Resources page with links to “recipes” for certain SLOB testing. The first installment is the recipe for loading 8TB scale SLOB 2.3 Multiple Schema Model with a 2-Socket Linux host attached to EMC XtremIO. Recipes will include (at a minimum) the relevant SLOB program output (e.g., setup.sh or runit.sh), init.ora and slob.conf.

Please keep an eye on the SLOB Resources page for updates…and (more...)

Oracle 12 and latches, part 2

In my previous post, I looked at non shared latches and how the latching is done by Oracle. This post is a description on how the latching works for shared latches.

The information is quite internal, if you landed on this page it might be a good idea to start with my first post on this topic: first post.

A famous example for shared latches is the ‘cache buffers chains’ latch.

For the sake (more...)

cloud control art?



I'm thinking of starting a gallery for cloud control images - here is the first painting in as you walk through the door



I call this "tidal wave hits redwood shores"

Other submissions gratefully received

Wait event bingo



How this for a random selection of wait events, some of these i never even heard of before



What seemed to have happened is that something had died and smon had decided to do parallel transaction recovery - this seemed to coinicide just around the time there was an out of space condition with the archive area which only last 60 seconds at most. The database returned to normal operation but not everything was working (more...)

My picks for UKOUG_Tech15

I went over the agenda for UKOUG_Tech15 and took my picks & suggestions.
Then I thought, why not share these…

MONDAY

Is Oracle the Best Language for Statistics
Brendan Tierney – Oralytics

Standard Edition Something for the Enterprise?
Ann Sjökvist – SE – JUST LOVE IT

Looking for Performance Issues in Oracle SE – Check what OraSASH Can do for You
Marcin Przepiorowski – Delphix

Silent but Deadly : SE Deserves Your Attention
Philippe Fierens (more...)

Oracle 12 and latches

Oracle DBAs who are so old that they remember the days before Oracle 11.2 probably remember the tuning efforts for latches. I can still recall the latch number for cache buffers chains from the top of my head: number 98. In the older days this was another number, 157.

But it seems latches have become less of a problem in the modern days of Oracle 11.2 and higher. Still, when I generate heavy (more...)