Author Archives: mgogala

About mgogala

I am a consultant with an extensive Oracle DBA experience. I have worked on very large databases. I have worked with OPS and RAC since its inception.I am also a published book writer, having published two books about PHP. This blog is about the challenges and adventures in my professional life. Sorry, no family pictures here.

ACFS 12.2 Quirks with defragmentation

I have a 12.2 RAC cluster in my lab, on two virtual machines. Checking out what acfsutil can do, I figured out that it can supposedly do defragmentation: [grid@rac1 ~]$ acfsutil defrag -help Usage: acfsutil [-h] command … # (Version … Continue reading

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RAC 12.2, part 2

Well, today was an interesting day. My ASM, configured with so much effort, stopped working: root@rac1 grid]# . ~grid/.bashrc [root@rac1 grid]# crsctl start ohasd CRS-4640: Oracle High Availability Services is already active CRS-4000: Command Start failed, or completed with errors. … Continue reading

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RAC 12.2

I am in the process of installing RAC 12.2. The installation procedure has undergone a significant change, for the better. It’s now much easier to install it. However, memory and disk requirements have skyrocketed. I needed to allocate 10GB of … Continue reading

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Rename Pluggable Database

I stumbled upon a convenient way to rename a pluggable database: SQL> alter system enable restricted session; System altered. SQL> alter database rename global_name to; Database altered. SQL> alter session set container=cdb$root; Session altered. SQL> select name from v$pdbs; … Continue reading

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Oracle 12c has a new feature related to optimizer dynamic sampling. The new level 11 is supposed to put the dynamic sampling on auto pilot and make the statistics available to other users. However, as soon as this was set, … Continue reading

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Oracle 12c, big table caching

In Oracle 11g,  there has been annoying change which has frequently had a seriously detrimental effect to the application performance. All tables, larger than 2% of SGA, were considered big tables and were read using direct reads into PGA, instead … Continue reading

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Smarter DG Broker in Oracle 12c

In Oracle 11G, DG Broker needed to be told whether the standby database was physical or logical. The command to add database in 11G was something like this: ADD DATABASE <DB Unique Name> AS CONNECT IDENTIFIER is <TNS Descriptor> MAINTAINED … Continue reading

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