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Dynamic Sampling vs. Extended Statistics

On datawarehouse databases, I frequently recommend increasing the level of dynamic sampling because:

East Coast Oracle Conference, (ECO 17)

So this week I’m back on the other coast, Raleigh, NC at ECO17 after last week in Seattle. I’ve switched from SQL Server to Oracle and we won’t discuss how many times I had to correct myself as I said, “transaction log” instead of “archive log” and pointed west instead of east for the ocean…My expression at times was similar to Obi Wan’s-

For the next month, I’ll be sticking to the Oracle side, as this is going to be a crazy month for travel.  My two sessions at ECO this week were well attended and I really enjoyed talking to folks and learning some new schtuff.

Little things worth knowing: scheduler jobs and Instance Caging

While updating material for a training class about Database Resource Management I briefly wondered if Instance Caging should apply for scheduler jobs as well. The obvious answer is “yes”, but I wanted to find proof. I hope I did in the end, and wanted to share how I got there.

The test environment

My system is based on the shiny new AMD Ryzen 7 1700X Eight-Core Processor, and it shows as 1s8c16t. I really like it! My database named DEMO is patched to August 2017 – to be precise. It’s difficult to test resource management, and specifically Instance Caging, with a dual-core laptop, so this machine should help!

Test setup

Apart from the database workload I am soon going to launch the system is otherwise idle. I set cpu_count to 4 and made sure I had a resource manager plan active:

Kudos to Pass Summit 2017

This week I had the opportunity to present at Microsoft’s Pass Summit, which was one of two events I had on my list for this year, (the other was Oracle Open World.) Although I’m still learning about all the events on the Microsoft side, unlike Oracle, where there’s one, massive event in San Francisco each fall, Microsoft has split their annual events into three to focus on each audience. In less than two months, there was MS Ignite in Florida, focused on tomorrow’s technology, IT Dev Connections, geared towards development and then this week, Pass Summit, for the Data Platform expert, (DBA and Data Scientist…)  I’m unsure of what events are going to have to leave my list I currently attend to fit these ones in, but somethings going to have to give.

Multitenant internals: INT$ and INT$INT$ views

This month, I’ll talk – with lot of demos – about multitenant internals at DOAG conference. CaptureMultitenantInternals

Multitenant dictionary: what is consolidated and what is not

The documentation says that for Reduction of duplication and Ease of database upgrade the Oracle-supplied objects such as data dictionary table definitions and PL/SQL packages are represented only in the root.

Unfortunately, this is only partly true. System PL/SQL packages are only in root but system table definition are replicated into all PDBs.

This post is an extension of a previous blog post which was on 12cR1. This one is on 12cR2.

Pass Summit 2017, 2nd Day, Thursday

Thursday started out calm, self-assured that I knew where I needed to be all day and was prepared.  I tweeted happily that I had found a lovely spot to work during the keynote, (day job!)

Yeah, this:

Quick history on database growth

AWR collects segment statistics, and this can be used to quickly understand an abnormal database growth. Here is a script I use to get, from the AWR history, the segments that have grown by more than 1% of the database size, in one hour.

First I must mention that this uses only the part of AWR which is not subject to additional option. This even works in Standard Edition:
------------------------------------ ----------- ------------------------------
control_management_pack_access string NONE

Dbvisit replicate – SQL Developer chart

Here is a quick SQL Developer report which display a chart about the Dbvisit replicate lag over the last hours

The idea is to have the following chart showing the lag in MINE and APPLY processes. Here is an example where I stopped the replication to show some lag.

The query is on the DBVREP.DBRSCOMMON_LAG_STATS on the APPLY side, which display the wallclock time with timestamp from the MINE and from the APPLY.

Here is the SQL Developer report .xml:

Max PDBs in Standard Edition

Here is a small warning. In Standard Edition, you may expect that the features that are not available for your edition are blocked, but in 12.2 you can create more than one PDB in Standard Edition, and you should set MAX_PDBS to prevent that.


In 12.1 Standard Edition, when you try to create more than one PDB (i.e with CON>ID > 3) you get an error:

ORA-65010: maximum number of pluggable databases created


But it seems that this has been lost in 12.2: