Automatic Deployment of CDBs with non-default database options in 12.1.0.2

I have written about the importance of automation in previous posts, and this one is following the same line. This time I wanted to test and document my experience with “golden database templates”. Wy? Because most DBAs will appreciate that there are more interesting things to do than to run “create database” scripts all day, so why not automate the process? For quite some time DBCA, or the Database Creation Assistant offers you the option (more...)

Using OSWatcher for system diagnostics

OSWatcher is a superb tool that gathers information about your system in the background and stores it in an (optionally compressed) archive directory. As an Oracle DBA I like the analogy with statspack: you make the tool available on the host in a location with – very important – enough available disk space and then start it. Most users add it to the startup mechanism their O/S uses- SysV init, upstart, or systemd for example (more...)

Little things worth knowing: auto-DOP or hint-which one takes precedence?

This is just another short post about one of the little things worth knowing. Assume you are on 12.1.0.2 for example and you want to know if parallel_degree_limit reliably keeps the degree of parallelism at bay, for all sessions and queries across the board. After all, every machine has finite CPU (and other) resources that shouldn’t be exhausted. Setting parallel_degree_limit of course only has an effect if you set parallel_degree_policy to limited, auto (more...)

Experimenting with the ZFSSA’s snapshot capability using the simulator part 2

In my last post I wrote down some notes about my experience while experimenting with the ZFSSA simulator. A simulator is a great way to get familiar with the user interface and general usability of a product. What I wanted to find out using the ZFSSA simulator was the answer to the question: “what happens to a clone of a database when I roll the master copy forward?”

In the first part of the (more...)

Experimenting with the ZFSSA’s snapshot capability using the simulator

Recently I have been asked how the Copy-on-Write cloning works on the ZFS Storage Appliance. More specifically, the question was about the “master” copy: did it have to be static or could it be rolled forward? What better than a test to work out how it works. Unfortunately I don’t have an actual system available to me at home so I had to revert to the simulator, hoping that it represents the real appliance accurately.

(more...)

Trouble with multiple SCAN listeners in 12c Release 1

Prompted by comments made by readers about my posts describing how to add a second SCAN in 12c Release 1 and problems regarding the listener_networks parameter I thought it was time to revisit the situation. I’m still running Oracle Linux 7.1/UEK3 (although that should not matter) but upgraded to 12.1.0.2.5. This is the release that is reportedly showing the odd behaviour. I don’t recall my exact version when I wrote (more...)

TABLE ACCESS INMEMORY FULL – but there may be more

While preparing to teach a class this week I have had the time to look into the In Memory (cost) option a bit closer. I noticed a few interesting things along the way and would like to share one of these here.

Background

One of the questions I was asking myself was:

“What happens if I scan segments that are within the IM area, and some are not?”

I was primarily thinking of joins in (more...)

Little things worth knowing: automatic generation of extended statistics in 12c Part II

In my last post I demonstrated an example how to use a PL/SQL package to monitor a workload in order to identify correlated columns. Such columns are good candidates for the creation of extended statistics since the optimiser does not assume that information stored in different columns may be related. Before starting my tests I invoked DBMS_STATS.SEED_COL_USAGE, which in turn increased Oracle’s attention level trying to find correlated columns. Eventually these have been identified (more...)

Little things worth knowing: automatic generation of extended statistics in 12c

When you are migrating to Oracle 12c I hope you might this post useful. I came across this feature when researching what’s new with Oracle 12c (and yes I still find lots of new ones I haven’t noticed before). This one is a bit hidden away in section 2.2.4.3 Automatic Column Group Detection of the 12c New Features Guide. And it’s a lot more complex than I first thought! In this first post (more...)

Example of Full Transportable Export to create a 12c PDB

The Cool Stuff

Oracle has introduced a new way of transporting data from one platform to another in 12c. The new feature is called “Full Transportable Export”. This enhancement works from 11.2.0.3 and later and is a great way to move data, as it allows for an easy-to-use combination of Export Data Pump and Transportable Tablespaces. The documentation specifically praises it as a means to move from an 11g Release 2 database into (more...)