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Jun 15, 2011
Jun 15, 2011

Global statistics high/low values when using DBMS_STATS.COPY_TABLE_STATS

There is a well-documented problem relating to DBMS_STATS.COPY_TABLE_STATS between partitions where high/low values of the partitioning key column were just copied verbatim from the source partition. This particular problem has now been patched (see 8318020.8). For background, see Doug Burns’ blog and his excellent paper which covers the whole topic of statistics on partitioned tables. This post Maintaining statistics on large partitioned tables on the Oracle Optimizer blog details what the dbms_stats.
May 26, 2011
May 26, 2011

Data Warehousing and Statistics in Oracle 11g - Automatic Optimizer Statistics Collection

Chucking a stick in the spokes of your carefully-tested ETL/BI … My opinion is that automated stats gathering for non-system objects should be disabled on Oracle Data Warehouses across all environments. All it does it cover up poor design or implementation which has omitted to consider statistics management. Once you get into the realms of millions or billions of rows of data, the automated housekeeping may well not have time to stat all of your tables on each run.
May 19, 2011
May 19, 2011

OBIEE performance - get your database sweating

Just because something produces the correct numbers on the report, it doesn’t mean you can stop there. How you are producing those numbers matters, and matters a lot if you have an interest in the long-term health of your system and its ability to scale. OBIEE is the case in point here, but the principle applies to any architecture with >1 tiers or components. Let me start with a rhetorical question.
Apr 11, 2011
Apr 11, 2011

Entertaining Exadata FUD from HP

Chris Mellor at The Register posted an interesting article a couple of days ago, entitled HP and Violin build Oracle Exadata killer. The slidedeck has been removed from HP’s FTP site, but a bit of Google magic throws up a couple of mirror copies. It’s an entertaining read (“Do a Proof of Concept! 94% win rate!! We can and do win against Exadata!!”), and a nice illustration of the FUD techniques that companies use in marketing their products against others.
Jan 8, 2011
Jan 8, 2011

Materialised Views - PCT Partition Truncation

I’ve been doing some work recently that involved the use of Materialised Views on Oracle 11g (11.1.0.7), particularly around PCT refresh. There are some things that are not clear from the documentation, or are actually bugs so far as I’m concerned, and I’ve detailed these below. In this example I was working on part of a DWH with c.2 millions rows aggregated up daily. One of the things that I spent a long time trying to get to work was Partition Truncation when using PCT refresh.
Jan 5, 2011
Jan 5, 2011

Oracle Whitepaper - “Best Practices for a Data Warehouse on Oracle Database 11g”

Poking around on My Oracle Support today, I found a link to a white paper dated November 2010, titled “Best Practices for a Data Warehouse on Oracle Database 11g”. It’s new to me and I’ve not noticed a blog post announcing it, so I thought I’d share it here. It’s by Maria Colgan, who has posted in the past on both the Inside the Oracle Optimizer blog and The Data Warehouse Insider blog.

Robin Moffatt

Robin Moffatt works on the DevRel team at Confluent. He likes writing about himself in the third person, eating good breakfasts, and drinking good beer.

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