This post takes a look on how to migrate the Oracle 12cR1 sample schemas to PPAS 9.4 (PostgreSQL Plus Advanced Server 9.4). I’ll not dig into how to install PPAS as this was described in detail some time ago. Just follow this post if you need a setup guide. If you wonder why I am doing this there are two…
By Franck Pachot . By default, In-Memory Column Store population is done in background, asynchronously. There are two hidden parameters that can change this behavior, let’s see how it works. Note that this is only good for research, those parameters are undocumented which means that they may not behave as you think they would. In a demo about in-Memory (slides,video)…
Recently at a customer I was confronted with a problem of restarting the Oracle Database 12c automatically on a Windows Server 2008 R2 x64. I installed Oracle 12.1.0.1.0 with a user of service in a domain who has member of the Group ORA_DBA. The authentication service is correctly set with the NTS parameter in the sqlnet.ora file. This Installation has…
Oracle Data Integrator is the ETL tool that Oracle has developed to enter into the world of Business Intelligence. Taking advantage of its incredible experience in database managing, Oracle has created an ETL tool that is flexible to use, powerful and that allows the integration of data coming from another sources. Agility of use Oracle Data Integrator uses various types…
By Franck Pachot . This 12c ‘wrong results’ issue is thoroughly described by Mike Dietrich (https://blogs.oracle.com/UPGRADE/entry/switch_off_rowsets_enabled_in) and I’ve nothing to add. This blog post is there to be used as a reference for the comment in the following recommendation that we give to our 12c customers: alter system set “_rowsets_enabled”=false comment=’see http://dbi-services.com/blog/_rowsets_enabled’ scope=both; Our best practice is to document any…
By Franck Pachot . In 12c the manual switchover to physical standby requires only one command (ALTER DATABASE SWITCHOVER) instead of two (ALTER DATABASE COMMIT TO SWITCHOVER on each database). We usually recommend to use the broker and I wanted to see if the broker uses that new command or not. Let’s compare the alert.log for both manual and broker…
By Franck Pachot . In the previous post we have seen how In-Memory Compression Unit map to the physical persistent storage – table extents. Let’s see now how they are mapped to column values, allowing to optimize the scan in a similar way as Exadata Storage Indexes. The examples below will illustrate IMCU pruning and IMCU skip filtering. Here are…
By Franck Pachot . Oracle In-Memory is an hybrid solution: an In-Memory Column Store in addition to the traditional Row Store. In the IMCS, data is stored in IMCU (In-memory compression units) and metadata is in SMU (Snapshot Metadata Units) In the row store, data is stored in datafile extents and metadata is stored in the dictionary (and in datafile…
By Franck Pachot . In the ‘traditional’ row store, the indexes are maintained at the same time as rows are changed. It’s different with the In-memory Column Store. Changes are maintained by background processes. When rows are changed, the Snapshot Metadata Units (SMU) logs the changes and In-Memory Compression Units (IMCU) are re-populated asynchronously. Let’s see an example. test case…
By Franck Pachot . Next Tuesday in Geneva I’m presenting Oracle In-Memory Column Store to Business Intelligence people at the Swiss BI Day After defining what is an analytic query, I show the different approaches to optimize that in Oracle, IMCS being the latest one. Here are some details about that slide. What is an analytic query? First definition –…
By Franck Pachot . At our bi-annual dbiXchange I was talking with Nicolas Jardot about his presentation on Result Cache (don’t forget Jérome witt session about RC at DOAG) where he has shown an unexpected behavior on ‘fetch first n rows queries’. That behavior – if it is not a bug – can also be a good thing when using…
By Franck Pachot . It don’t want to rub salt in the wound about 12c upgrades and Adaptive Dynamic Sampling being overzealous, but here is a case with an unexpected consequence: you see nothing in the ‘Database Feature Usage’ since migration. The photo novel starts like this: we are in September and when I check the ‘Database Feature Usage’ page…
