Oracle

OCM 12c preparation: Materialized View explain_rewrite

By Franck Pachot . When I passed the OCM 11g exam, I had to prepare the 'Manage Materialized Views to improve rewrite' topic. Now that I'm preparing the 12c upgrade I checked quickly what I've(…)

DataGuard broker properties – Part I: imported parameters

By Franck Pachot . When you are using the DataGuard Broker, you should always use the broker (with DGMGRL or OEM) to change the parameters that are managed, rather than changing them with ALTER SYSTEM. But do you know which(…)

RESULT_CACHE hint expiration options

By Franck Pachot . The result cache is very nice when base tables are static: get the result without any buffer get, without any join or sorts. But as soon as any DML occurs on one of the tables(…)

Multitenant vs. schema based consolidation

By Franck Pachot . If you want to install multiple instances of a software, for example you host the ERP for several companies or subsidiaries, you have 3 solutions: have one database and multiple schema have multiple databases have(…)

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(…)

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(…)

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(…)

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(…)