Oracle Indexes

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Exadata Storage Indexes Part II – Differences With Database Indexes (Space Dementia)

Let’s explore some of the key differences between Storage Indexes (SI) and Database Indexes (DI). In no particular order, they include: SIs are structures that exist only within the storage servers of an Exadata box, while DIs logically exist and can be accessed within the database servers. SIs are purely memory only structures while DIs are […]

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Exadata Storage Indexes – Part I (Beginning To See The Light)

Thought I might discuss Exadata Storage Indexes, explore what they are, how they work and discuss their advantages and disadvantages. Following is but a brief introduction on this very cool Exadata feature. A Storage Index basically maintains summary information about database table data down on the Exadata storage servers. The information consists of the minimum value, the maximum […]

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Indexes: Oracle11g New Features Presentation (Get Back)

I’m in the early stages of compiling an Oracle12c Indexes New Features presentation so I thought I might make available the 11g version I’ve presented previously at Oracle OpenWorld and InSync conferences: http://richardfoote.files.wordpress.com/2012/09/oracle-indexing-new-feat... Enjoy

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E4 2012 Enkitec Extreme Exadata Expo (Blue Jean)

I’m very pleased to have been invited to speak at the E4 2012 Enkitec Exadata Expo to be held in Dallas, USA on 13-14 August. It’s basically the first ever conference that’s dedicated exclusively to Oracle’s exciting Exadata platform. It should be a fabulous event, featuring some of the best Oracle talent going around, including Jonathan Lewis, Tanel [...]

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Indexes vs. Full Table Scan: Picture vs. 1000 Words (Pictures Of Lily)

I’m in the process of writing a number of new presentations and in one I’ve included a favorite little graph of mine that I’ve used over the years to help illustrate the relationship between the cost of using an index vs. the cost of using a Full Table Scan (FTS). It’s occurred to me that I’ve never actually [...]

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Cost of Virtual Indexes (Little Lies)

I’ve previously discussed Virtual Indexes and how they can be used to do basic “what if” analysis if such an index really existed. However, a recent comment on the OTN forums regarding using them to compare index costs made me think a follow-up post regarding the dangers of Virtual Indexes might be warranted. The big advantage of [...]

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Index Rebuild – Does it use the Index or the Table ? (Nothing Touches Me)

A common question that gets asked is does Oracle access the index itself or the parent table during an index rebuild to extract the necessary data for the index ? Thought it might be worth a blog post to discuss. Now if the index is currently in an UNUSABLE state, then Oracle clearly can’t use the existing [...]

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IOT Secondary Indexes – The Logical ROWID Guess Component Part I (Lucky)

As discussed previously, an index entry within a Secondary Index on an Index Organized Table (IOT) basically consists of the indexed column(s) and the Logical Rowid, the PK column(s) and a “guess” to the physical block in the IOT containing the corresponding row. Let’s discuss this “guess” component in a bit more detail. When the Secondary [...]

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IOT Secondary Indexes: Primary Key Considerations (Beauty And The Beast)

As discussed previously, one of the nice features of an IOT Secondary Index is that it contains the mandatory Primary Key of the IOT, which is always maintained and can be used to access the necessary rows of the IOT regardless of  row movement within the IOT itself. This can also be beneficial if only the PK [...]

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Indexed Organized Tables – An Introduction to IOT Secondary Indexes (A Second Face)

Man, its been ages since I had free time to update the blog, what with birthday parties to organise, Roger Water concerts to attend and Radiohead concerts in the planning !! OK, time to take an initial look at Secondary Indexes for Index Organized Tables (IOTs). If the IOT needs to be accessed via the Primary Key (PK) column(s), [...]

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