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Oracle Team

Data Guard: always set db_create_file_dest on the standby

By | Oracle | 6 Comments

By Franck Pachot . The file name convert parameters are not dynamic and require a restart of the instance. An enhancement request was filled in 2011. I mentioned recently on Twitter that it can be annoying with Active Data Guard when a file on the primary server is created on a path that has no file name conversion. However, Ian Baugaard mentioned that there is a workaround for this specific case because db_create_file_dest is dynamic:

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Oracle Team

18c: No Active Data Guard required (and detected) when only CDB$ROOT and PDB$SEED are opened in read-only

By | Oracle | One Comment

By Franck Pachot . When you clone a PDB on the primary CDB, you want that the same is automatically done on the standby ones. Unfortunately, for this operation, the CDB must be opened read-only. In 12.1 even the PDB needed to be opened read-only (Ludovico Caldara reported this in his blog). This, as far as I know, was fixed in 12.2 where MRP reads the files without the need to have the PDB opened….

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Oracle Team

18c new Lost Write Protection

By | Oracle | 5 Comments

By Franck Pachot . There are many layers between the Oracle Database pwrite() calls and the physical sector written on disk: filesystem, logical volume, SAN or NAS, with a lot of smart software running for Virtualisation, Compression, Snapshotting, Synchronisation… Are you sure that the changes you made to your data is actually persisted on disk, completely and without any corruption? In case of bug or crash in the storage layer, it may happen that only…

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Oracle Team

18c, Cloud First and Cloud Only features: think differently

By | Cloud, Database Administration & Monitoring, Oracle | One Comment

By Franck Pachot . Remember the times when the Oracle Software features were the same on all platforms? Where Oracle databases could be ported to any relevant platform? Where we were able to try any feature, freely, by downloading the latest release software? Now we need to think differently. Because: The new software is released on Cloud first The major new features will never be available on-premises The Cloud here means the Oracle Cloud –…

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Oracle Team

Server process name in Postgres and Oracle

By | Oracle, Postgres | One Comment

By Franck Pachot . Every database analysis should start with system load analysis. If the host is in CPU starvation, then looking at other statistics can be pointless. With ‘top’ on Linux, or equivalent such as process explorer on Windows, you see the process (and threads). If the name of the process is meaningful, you already have a clue about the active sessions. Postgres goes further by showing the operation (which SQL command), the state…

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Oracle Team

Multitenant, PDB, ‘save state’, services and standby databases

By | Oracle | 3 Comments

By Franck Pachot . Creating – and using – your own services has always been the recommendation. You can connect to a database without a service name, though the instance SID, but this is not what you should do. Each database registers its db_unique_name as a service, and you can use it to connect, but it is always better to create your own application service(s). In multitenant, each PDB registers its name as a service,…

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Oracle Team

Keep your orapw password file secure

By | Oracle | 2 Comments

By Franck Pachot . This is a small demo I did when I’ve found a database password file (orapw) lying around in /tmp with -rw-rw-rw- permissions, to show how this is a bad idea. People think that the orapw file only contains hashes to validate a password given, and forget that it can be used to connect to a remote database without password.

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Clemens Bleile

Transfer redo in async-mode to the Gold/Master copy of the Production DB for ACFS snapshots

By | Database Administration & Monitoring, Oracle | 2 Comments

If you store your databases on the cluster filesystem ACFS you may use the provided Perl-script gDBClone from OTN to clone databases or create snapshot databases. It is an interesting approach to create clones from the Production DB in minutes regardless of the production DB size. What you do is to create a standby DB from your production DB on a separate cluster and use that standby DB as a Gold/Master copy for ACFS snapshots….

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Oracle Team

Unstructured vs. structured

By | Oracle | One Comment

By Franck Pachot . The title of this blog post was: “Tracing DBMS_RCVMAN for reclaimable archivelogs” until I started to write the conclusion… In a previous post I mentioned that there’s a bug with archivelog deletion policy when you want to mention both the ‘BACKED UP … TIMES TO …’ and ‘APPLIED’ or ‘SHIPPED’ as conditions for archived logs to be reclaimable. I opened a SR, they didn’t even try to reproduce it (and I…

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Oracle Team

Archivelog deletion policy on Data Guard configuration

By | Oracle | 11 Comments

By Franck Pachot . The deletion policy on a dataguard configuration should be: CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON ALL STANDBY; for the site where you don’t backup. It can be the standby or the primary. and: CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON ALL STANDBY BACKED UP 1 TIMES TO DISK; for the site where you do the backups. It can be the primary or the standby. I’ve always configured it in this…

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