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Oracle

Petre Radut

When you change the UNDO_RETENTION parameter, the LOB segment’s retention value is not modified

By | Database Administration & Monitoring, Database management, Development & Performance, Hardware & Storage, Oracle | No Comments

Below, I will try to explain, a particular case for the general error : ORA-01555 snapshot too old error.. Normally, when we have this error, we are trying to adapt the retention parameters or to tune our queries. SQL> show parameter undo; NAME TYPE VALUE ———————————— ———– —————————— temp_undo_enabled boolean FALSE undo_management string AUTO undo_retention integer 3600 –extended from 900, undo_tablespace string UNDOTBS1 But, are some scenarios where the above rule is not working . We…

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Lazhar Felahi

SQL Tuning – Mix NULL / NOT NULL Values

By | Development & Performance, Oracle | No Comments

One of the difficulty when writing a SQL query (static SQL) is to have in the same Where Clause different conditions handling Null Values and Not Null Values for a predica. Let’s me explain you by an example : Users can entered different values for a user field from an OBI report: – If no value entered then all rows must be returned. – If 1 value entered then only row(s) related to the filter…

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Jérôme Dubar

How to patch your ODA lite to 18.3.0.0.0

By | Database Administration & Monitoring, Database management, Hardware & Storage, Oracle | No Comments

Even you don’t need 18c, or you’re not ready for this release, this patch will also update your 11gR2, 12cR1 and 12cR2 databases to the latest PSU available on ODA, it means for example the patchset from last July if you’re using 12cR1. Here is how to apply this latest patch for your ODA lite. In this example, the patch was applied on an X6-2S ODA running on previous release: 12.2.1.4.0. 1) Download the patch…

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Petre Radut

Create a primary database using the backup of a standby database on 12cR2

By | Database Administration & Monitoring, Database management, Oracle | No Comments

The scope of this blog will be to show how to create a primary role database based on a backup of a standby database on 12cR2. Step1: We are assuming that an auxiliary instance has been created and started in nomount mode. rman target / restore primary controlfile from ‘backup_location_directory/control_.bkp’; exit; By specifying “restore primary” , will modify the flag into the controlfile, and will mount a primary role instance instead of a standby one….

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Petre Radut

Recover a corrupted datafile in your DataGuard environment 11G/12C.

By | Database Administration & Monitoring, Database management, Development & Performance, Oracle | No Comments

On a DG environment, a datafile needs to be recovered on the STANDBY site, in two situations : when is deleted or corrupted. Below, I will explain  how to recover a corrupted datafile, in order to be able to repair the Standby database, without to be necessary to restore entire database. Initial situation : DGMGRL> connect / Connected to “PROD_SITE2” Connected as SYSDG. DGMGRL> show configuration; Configuration – CONFIG1 Protection Mode: MaxPerformance Members: PROD_SITE2 -…

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Jérôme Dubar

ODA : Free up space on local filesystems

By | Database Administration & Monitoring, Oracle | No Comments

Introduction When you work on ODA you sometimes get struggled with local filesystem free space. ODA has terabytes of space on data disks, but local disks are still limited to a raid-1 array of 2x 480GB disks. And only few GB are dedicated to / and /u01 filesystems. You do not need hundreds of GB on these filesystems, but I think that you prefer to keep at least 20-30% of free space. And if you…

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