Do you know the difference between exp/imp and expdp/impdp when it comes to importing HCC compressed data in Exadata?
If not, then follow me through two examples. This is on 184.108.40.206/220.127.116.11.1 but applies to all database releases you can have on Exadata. The task at hand is to export a table (which happens to be non-partitioned and HCC compressed for query high) and import it into a different user’s schema. This is quite a common approach when migrating data from a non-Exadata system into an Exadata system. You could for example pre-create the DDL for the tables and implement HCC before even importing a single row. When importing the data, the partitions’ HCC attributes will be honoured and data will be inserted compressed. Or won’t it?
Here are the slides of a presentation I did at the IOUG Virtual Exadata conference in February. I’m explaining the basics of some new Oracle 12c things related to Exadata, plus current latest cellsrv improvements like Columnar Flash Cache and IO skipping for Min/Max retrieval using Storage Indexes:
Note that Christian Antognini and Roger MacNicol have written separate articles about some new features:
Before discussing the Exadata-specific feature, let’s review what the database engine can do independently of whether Exadata is used. To execute queries containing the
max functions efficiently, two specific operations are available with B-tree indexes defined on the column referenced in the
max function. The first,
INDEX FULL SCAN (MIN/MAX), is used when a query doesn’t specify a range condition. In spite of its name, however, it performs no full index scan. It simply gets either the rightmost or the leftmost index key:
Please join me in welcoming the Exadata product documentation to the internet. It’s been a long time coming, but glad it’s finally made an appearance!
In part 1 of the series I tried to explain (probably a bit too verbose when it came to session statistics) what the effect is of delayed block cleanout and buffered I/O. In the final example the “dirty” blocks on disk have been cleaned out in the buffer cache, greatly reducing the amount of work to be done when reading them.
Travel time is writing time and I have the perfect setting for a techie post. Actually I got quite excited about the subject causing the article to get a bit longer than initially anticipated. In this part you can read about block cleanouts when using buffered I/O. The next part will show how this works using direct path reads and Smart Scans.
The article ultimately aims at describing the enhancements Exadata brings to the table for direct path reads and delayed block cleanouts. Delayed block cleanouts are described in Jonathan Lewis’s “Oracle Core”, and in one of his blog posts, so here’s just a summary.
The delayed block cleanout
Heute wurde auf "informatik-aktuell.de" ein aktueller Artikel von mir veröffentlicht. Es geht darin um die Analyse eines Falles bei einem meiner Kunden, der auf Exadata nicht die erwartete Performance erreicht hat.
In dem Artikel werden unterschiedliche Abfrage-Profile analysiert und erklärt, wie diese unterschiedlichen Profile die speziellen Features von Exadata und In-Memory beeinflussen.
It's webinar time again.
Join me on Wednesday, January 28th at AllThingsOracle.com for a session based on a real world customer experience.
The session starts at 3pm UK (16:00 Central European) time. The webinar is totally free and the recording will made available afterwards.
Here's the link to the official landing page where you can register and below is the official abstract:
These I consider the most important points about Exadata Patching:
MOS Note 888828.1 is your first read whenever you think about Exadata Patching
Expect quarterly bundle patches for the storage servers and the compute nodes. The other components (Infiniband switches, Cisco Ethernet Switch, PDUs) are less frequently patched and not on the picture therefore.
Every DBA working with the Oracle database must have seen memory dumps in tracefiles. It is present in ORA-600 (internal error) ORA-7445 (operating system error), system state dumps, process state dumps and a lot of other dumps.
This is how it looks likes: