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March 2015

12c MView refresh

Some time ago I wrote a blog note describing a hack for refreshing a large materialized view with minimum overhead by taking advantage of a single-partition partitioned table. This note describes how Oracle 12c now gives you an official way of doing something similar – the “out of place” refresh.

I’ll start by creating a matieralized view and creating a couple of indexes on the resulting underlying table; then show you three different calls to refresh the view. The materialized view is based on all_objects so it can’t be made available for query rewrite (ORA-30354: Query rewrite not allowed on SYS relations) , and I haven’t created any materialized view logs so there’s no question of fast refreshes – but all I intend to do here is show you the relative impact of a complete refresh.

Try Oracle 12c VM with Delphix download


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 photo by #212124;" title="Go to Jose Maria Cuellar's photostream" href="https://www.flickr.com/photos/cuellar/" data-track="attributionNameClick" data-rapid_p="67">Jose Maria Cuellar (CC 2.0)

Thanks to Leighton Nelson who pointed out  that :

Oracle has a pre-installed Linux VM with 12c

Delphix as well has a pre-installed   trial version 

Try Oracle 12c VM with Delphix download


9104210308_a63b5ae5c4_z
 photo by #212124;" title="Go to Jose Maria Cuellar's photostream" href="https://www.flickr.com/photos/cuellar/" data-track="attributionNameClick" data-rapid_p="67">Jose Maria Cuellar (CC 2.0)

Thanks to Leighton Nelson who pointed out  that :

Oracle has a pre-installed Linux VM with 12c

Delphix as well has a pre-installed   trial version 

IOUG Collaborate 2015

I will be presenting two topics in IOUG Collaborate 2015 in Vegas. Use the show planner and add my presentations to your schedule </p />
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Oracle Exadata Performance: Latest Improvements and Less Known Features

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:
http://antognini.ch/2015/03/exadata-storage-index-minmax-optimization/ https://blogs.oracle.com/smartscan-deep-dive/entry/examining_the_new_col... Enjoy!
 

Oracle Exadata Performance: Latest Improvements and Less Known Features

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:

Oracle Exadata Performance: Latest Improvements and Less Known Features

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:
http://antognini.ch/2015/03/exadata-storage-index-minmax-optimization/ https://blogs.oracle.com/smartscan-deep-dive/entry/examining_the_new_col... Enjoy!
 

Exadata Storage Index Min/Max Optimization

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 min or max functions efficiently, two specific operations are available with B-tree indexes defined on the column referenced in the min or 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:

Oracle system V shared memory indicated deleted

This article is written with examples taken from an (virtualised) Oracle Linux 6u6 X86_64 operating system, and Oracle database version 12.1.0.2.1. However, I think the same behaviour is true for Oracle 11 and 10 and earlier versions.

Probably most readers of this blog are aware that a “map” of mapped memory for a process exists for every process in /proc, in a pseudo file called “maps”. If I want to look at my current process’ mappings, I can simply issue:

NYOUG Spring General Meeting

The New York Oracle User Group held their Spring General Meeting recently and I was presenting there about the Data Guard Broker and also about the Recovery Area.

Many thanks to the board for organizing this event, I really enjoyed being there! Actually, the Broker demonstration went not so smoothly – always dangerous to do things live – but I managed to get out of the mess in time and without losing too much of the message I wanted to get through. At least that’s what I hope ;-)