Oracle

Oracle recovery concepts

I’ve published a while ago a twitter thead on some Oracle recovery concepts. For those who are not following twitter, I’m putting the whole thread here:   🔴⏬ Here I start a thread(…)

A change in full table scan costs in 19c?

During tests in Oracle 19c I recently experienced this: cbleile@orcl@orcl> select * from demo4 where m=103; cbleile@orcl@orcl> select * from table(dbms_xplan.display_cursor); ... --------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | --------------------------------------------------------------------------- |(…)

Oracle disables your multitenant option when you run on EC2

I have installed Oracle 19.6 on an EC2 for our Multitenant Workshop training. And of course, during the workshop we create a lot of PDBs. If you don't have paid for the Enterprise Edition plus the(…)

Oracle 20c SQL Macros: a scalar example to join agility and performance

By Franck Pachot . Let’s say you have a PEOPLE table with FIRST_NAME and LAST_NAME and you want, in many places of your application, to display the full name. Usually my name will be displayed as ‘Franck Pachot’ and(…)

Speed up datapump export for migrating big databases

Introduction Big Oracle databases (several TB) are still tough to migrate to another version on a new server. For most of them, you’ll probably use RMAN restore or Data Guard, but datapump is always a cleaner way to migrate. With(…)

Oracle 20c Data Guard : Validating a Fast Start Failover Configuration

By Mouhamadou Diaw In Oracle 20c, we can now validate a Fast Start Failover configuration with the new command VALIDATE FAST_START FAILOVER. This command will help identifying issues in the configuration. I tested this new feature. The Fast Start(…)

Oracle 20c : The new PREPARE DATABASE FOR DATA GUARD

By Mouhamadou Diaw As you may know, Oracle 20c is in the cloud with new features. The one I have tested is the PREPARE DATABASE FOR DATA GUARD. This command configures a database for use as a primary database(…)

SQLNET.EXPIRE_TIME and ENABLE=BROKEN

By Franck Pachot . Those parameters, SQLNET.EXPIRE_TIME in sqlnet.ora and ENABLE=BROKEN in a connection description exist for a long time but may have changed in behavior. They are both related to detecting dead TCP connections with keep-alive probes. The former(…)

odacli create-database extremely slow on ODA X8-2 with 19.5

Introduction ODA X8-2, in the S, M or HA flavour, is the new database appliance from Oracle. But as a brand new product, you can experience troubles due to the lack of maturity. This time, it concerns database creation that(…)

How SQL Server MVCC compares to Oracle and PostgreSQL

By Franck Pachot . Microsoft SQL Server has implemented MVCC in 2005, which has been proven to be the best approach for transaction isolation (the I in ACID) in OLTP. But are you sure that writers do not block readers(…)