Oracle

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(…)

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(…)

Show the Top 10 events from latest AWR snapshot

By Franck Pachot . Want to display a specific section from the latest AWR report? I'll share the script I use to get something like that:(…)

Parallel DML in 12c

By Franck Pachot . Following a question from Randolf Geist (who can imagine that there is something about parallel query that Randolf didn’t know?), I get back to some notes I’ve taken when 12c was out and I’ve(…)

Can you have pending system statistics?

By Franck Pachot . Your system statistics seems to be wrong and you want to gather or set more relevant ones. But you don’t want to see all your application execution plans changing between nested loops and hash joins.