Oracle 12.2 underscores appear in SPFILE – be aware when you flashback

I did blog in the past weeks about Fallback Strategies with Flashback Database. But two of my reference customers came across an interesting issue when they tried to fallback: Oracle 12.2 underscores appear in the SPFILE – magically – and prevent the fallback using the existing SPFILE. Oracle 12.2 underscores appear in SPFILE – be aware when you flashback In one case it happened during a test, in the other case it happened during a live fallback after the Data Guard Broker has interfered with the upgrade causing real trouble. In both cases the SPFILE sits in ASM. Both customers…

SGA_MIN_SIZE in Oracle Database 12.2

I did summarize all new init.ora/spfile parameters in Oracle Database 12.2.0.1 a while ago: New SPFILE parameters in Oracle Database 12.2.0.1 And one caught Roy’s and my attention: SGA_MIN_SIZE. When we present this new parameter as part of the Multitenant slides in our workshops, some people ask themselves: “What happens if I oversubscribe such a parameter?” For example, if SGA_TARGET=4G and I have 10 PDBs and define in each of them SGA_MIN_SIZE=500M. Will the 9th and 10th PDB not startup anymore? Or will the 7th PDB already in trouble as the CDB$ROOT will need some SGA portion as well? None…

Parameter Recommendations for Oracle Database 12c – Part II

See also: Parameter Recommendations for Oracle Database 12c – Part I Time for a new round on Parameter Recommendations for Oracle Database 12.1.0.2. The focus of this blog post settles on very well known parameters with interesting behavior. This can be a behavior change or simply something we’d like to point out. And even if you still work on Oracle Database 11g some of the below recommendations may apply to your environment as well. Preface Again, please be advised – the following parameter list is mostly based on personal experience only. Some of them are officially recommended by Oracle Support. Always use proper testing…

Parameter Recommendations for Oracle Database 12c – Part I

See also: Parameter Recommendations for Oracle Database 12c – Part II A few weeks ago we’ve published some parameter recommendations including several underscores but based on an internal discussion (still ongoing) we decided to remove this entry and split up the tasks. The optimizer team will take over parts of it and I’ll post an update as soon as something is published. Preface Please be advised – the following parameter list is mostly based on personal experience only. Some of them are officially recommended by Oracle Support. Always use proper testing mechanisms. We strongly recommend SQL Performance Analyzer to verify the effect of any of those…

What happened to the blog post about “12c parameters”?

Two weeks ago I published a blog post about Parameter Recommendations for Oracle Database 12.1.0.2. And I took it down a day later. Why that? I’ve got a lot of input from external sources for the “Parameter” blog post. And I’d like to thank everybody who contributed to it, especially Oracle ACE Ludovico Caldara. Generally there was a bit of a misunderstanding internally about whether we should “advertise” underscore parameters to cure some misbehavior of the database. In 99% of all cases I’d agree that underscores are not a good solution – especially when it comes to database upgrades as…

New (some undocumented) Parameters in Oracle 12.1.0.2

Every release offers some surprises – even to myself 😉 Right now Roy and I are in the final steps to refresh our big slide deck to the new layout, but more important, to have Oracle 12.1.0.2 information included as well (were necessary). So I did my usual “compare parameters” query between releases – getting unusual surprises this time. This is the list of new parameters introduced with the patch set Oracle Database 12.1.0.2. Where applicable I have added the link to the doc. But as you may recognize not all of them are explained in the doc 😉 DBFIPS_140…

Why you shouldn’t set OPTIMIZER_FEATURES_ENABLE

Roy today answered an interesting question on one of our internal mailing lists. And this reminds me to pick up that piece of information as we see this quite often on customer sites, especially after upgrades or migrations. People set OPTIMIZER_FEATURES_ENABLE (OFE) to revert the optimizer’s behaviour to another pre-current release. That’s what a lot of people think this parameter does. But in fact this is not true. Even though our documentation states it: OPTIMIZER_FEATURES_ENABLE acts as an umbrella parameter for enabling a series of optimizer features based on an Oracle release number. For example, if you upgrade your database from release 10.1…

Upgrade – and an interesting surprise

Patchset 11.2.0.2 is out there for a long, looong time. But still Roy and me – and unfortunately our customers – sometimes experience some nice surprises after upgrade. Roy did work on the weekend with a financial institution customer in the US to support them during their go-live on Oracle 11.2.0.2 with several systems. It was well tested and long planned. And overall the whole process went well except for one database (see Roy’s entry below on the change with JOB_QUEUE_PROCESSES in 11.2.0.2). Yesterday I’ve received a text message from Roy to have a closer look into a service request…