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Richard Foote

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Focusing Specifically On Oracle Indexes, Database Administration and Some Great Music
Updated: 18 hours 4 min ago

12.1.0.2 Introduction to Zone Maps Part III (Little By Little)

Mon, 2014-11-24 00:16
I’ve previously discussed the new Zone Map database feature and how they work in a similar manner to Exadata Storage indexes. Just like Storage Indexes (and conventional indexes for that manner), they work best when the data is well clustered in relation to the Zone Map or index. By having the data in the table […]
Categories: DBA Blogs

Index Advanced Compression vs. Bitmap Indexes (Candidate)

Thu, 2014-10-30 23:59
A good question from Robert Thorneycroft I thought warranted its own post. He asked: “I have a question regarding bitmapped indexes verses index compression. In your previous blog titled ‘So What Is A Good Cardinality Estimate For A Bitmap Index Column ? (Song 2)’ you came to the conclusion that ‘500,000 distinct values in a 1 […]
Categories: DBA Blogs

12.1.0.2 Introduction to Zone Maps Part II (Changes)

Thu, 2014-10-30 00:45
In Part I, I discussed how Zone Maps are new index like structures, similar to Exadata Storage Indexes, that enables the “pruning” of disk blocks during accesses of the table by storing the min and max values of selected columns for each “zone” of a table. A Zone being a range of contiguous (8M) blocks. I […]
Categories: DBA Blogs

Index Compression Part VI: 12c Index Advanced Compression Block Dumps (Tumble and Twirl)

Thu, 2014-10-09 01:01
Sometimes, a few pictures (or in this case index block dumps) is better than a whole bunch of words :) In my previous post, I introduced the new Advanced Index Compression feature, whereby Oracle automatically determines how to best compress an index. I showed a simple example of an indexed column that had sections of index entries that were […]
Categories: DBA Blogs

Index Compression Part V: 12c Advanced Index Compression (Little Wonder)

Thu, 2014-10-02 04:28
I’ve finally managed to find some free time in the evening to write a new blog piece :) This will have to be the record for the longest time between parts in a series, having written Part IV of this Index Compression series way way back in February 2008 !! Here are the links to the previous articles […]
Categories: DBA Blogs

12.1.0.2 Introduction to Zone Maps Part I (Map Of The Problematique)

Wed, 2014-09-03 02:06
Zone Maps are new index-like structures that enables the “pruning” of disk blocks during accesses of the table by storing the min and max values of selected columns for each “zone” of a table. A zone is simply a range of contiguous blocks within a table. Zone Maps are similar in concept to Exadata storage […]
Categories: DBA Blogs