All articles

Oracle Log Writer and Write-Ahead-Logging

By Franck Pachot . I posted a tweet with a link to a very old document – 20 years old – about ‘internals of recovery’. It’s a gem. All the complexity of the ACID mecanisms of Oracle are(…)

Oracle Database Cloud Service – My first trial

By Franck Pachot . The cloud has been annouced, I want to try. From the cloud.oracle.com/database website, there is Trial only for the ‘Database Schema Service’ so I asked fot it, received an e-mail with connection info and it(…)

Quickly create a hundred databases and users

Do you need a hundred databases and users for training etc. in PostgreSQL? Just a few lines of code: [postgres8@oel7 data]$ cat create_databases.sh #!/bin/bash NUMOFDBS=100 for i in `seq ${NUMOFDBS}`; do psql -q -c "create user u${i}(…)

RAC buffer states: XCUR, SCUR, PI, CI

By Franck Pachot . In RAC, blocks are copied across instances by the Global Cache Service. In single instance, we have only two status: CR for consistent read clones where undo is applied, and CUR for the current version(…)

another way to list invalid objects

How often did I type a query like this to list the invalid objects in a database? select count(*) from dba_objects where status 'VALID'; -- and user in/not in Today I learned another way to do the same. There(…)

Multithreaded 12c and ‘connect / as sysdba’

By Franck Pachot . In Oracle 12c you can run Oracle processes as operating system threads, lowering the number of OS processes. But you can’t use OS authentification: you need to provide a password. Here is a way to(…)

SQL Server 2016 : availability groups and the new SSISDB support

This blog post is focused on the new supportability of SSIDB catalog on AlwaysOn architecture. Others studies are available here: New database issue level detection for automatic failover Potential features in standard(…)

2 ways to move archivelogs – both need RMAN

By Franck Pachot . The database must know where are the files. If you move them from the OS, the database will not be aware of it. But there is a database tool to copy or move files and(…)

Buffer pool advisory in AWR

By Franck Pachot . In Oracle memory advisors: how relevant ? I said that advisors are calculating their recommendations from statistics cumulated since the begining of the instance, even in AWR which is supposed to cover only a(…)

Does the block size matter?

By Franck Pachot . The default block size is 8k in Oracle. This is the most common. Sometimes, people create the database with 16k block size for datawarehouses. You can also find some 32k block size, but less common(…)