Database Administration & Monitoring

MySQL – Foreign keys and “Cannot delete or update a parent row: a foreign key constraint fails” error

As you know, foreign keys establish a sort of relationship between 2 tables. MySQL requires InnoDB storage engine to support foreign keys. In our example, we have the following parent table in a MySQL 5.7.21 server: mysqld3-(root@localhost) [sakila]> show create(…)

EDB Failover Manager 3.0 and PostgreSQL 10.1

By Mouhamadou Diaw Edb Failover Manager edb-efm30 is now released and supports PostgreSQL 10.1. Efm is an EDB tool which can be used to perform a switchover and a failover in a PostgreSQL standby environment. In this blog(…)

ODA – Reducing number of cores : Getting error DCS-10045

To perform some tests in order to determine the accurate number of cores to be used by the database application, I had to increase and decrease the number of CPU cores on an ODA using the DCS stack.  When increasing(…)

ODA migration challenges: Non-OMF to OMF + 11.2.0.3 to 11.2.0.4

To do some application and performances tests, I had to copy a database from a third party Linux server to an ODA X7-2M. Looks pretty simple on the paper, but 2 small challenges came into the game. The first was(…)

ORA-12547 TNS lost contact on SLES12 and oracle 11.2.0.x

On a client’s site, I have migrated successfully Oracle 12c databases from RedHat to SLES12 without any problem. I encountered a problem doing the same work with Oracle 11.2.0.3 and oracle 11.2.0.4 on SLES 12. Once I have moved the(…)

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

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(…)

Configuring huge pages for your PostgreSQL instance, Debian version

In the last post we had a look at how you can configure huge pages on RedHat and CentOS systems. For Debian and Debian based systems the procedure is different as Debian does not come with(…)

Configuring huge pages for your PostgreSQL instance, RedHat/CentOS version

Almost every PostgreSQL I get in touch with is not configured to use huge pages, which is quite a surprise as it can give you a performance boost. Actually it is not the PostgreSQL instance you need(…)

New SHA-2 functions showing up in PostgreSQL 11

A recent commit announced new SHA-2 functions coming up in PostgreSQL 11. Until now you can use the md5 function to generate hashes for test data or whatever you want. This commit adds more(…)

How to prevent RMAN archivelog backup from log switch

When RMAN backups archivelogs, it does a logswitch before backing up all archivelogs. In some cases this log switching should be suppressed. This can be done with expression “until time ‘sysdate'”, which actually filters nothing. For example: backup archivelog until(…)