Oracle Indexes

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Index Column Order – Impact On Index Branch Blocks Part I (Day-In Day-Out)

I recently replied on Twitter to some comments regarding an excellent blog post by Franck Pachot – Covering indexes in Oracle, and branch size, where I disagreed somewhat with one of the conclusions stated in the post: “ensure that selective columns appear as early as possible (without compromising the index access efficiency of course) in order to […]

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Announcing July/August Australian Dates: “Oracle Indexing Internals and Best Practices” Seminar

I’m very excited to announce new Australian dates for my highly acclaimed “Oracle Indexing Internals and Best Practices” seminar. This is a must attend seminar of benefit to not only DBAs, but also to Developers, Solution Architects and anyone else interested in designing, developing or maintaining high performance Oracle-based applications. It’s a fun, but intense, […]

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18c Scalable Sequences Part III (Too Much Rope)

I previously looked in Part I and Part II how Scalable Sequences officially released in 18c can reduce index contention issues, by automatically assigning a 6 digit prefix to the sequence value based on the instance ID and session ID of the session. We need to be careful and consider this 6 digit prefix if […]

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ODTUG Kscope18 Conference: Change of Presentation Times

For those of you that were planning to attend my presentations at the upcoming ODTUG Kscope18 Conference in Orlando (yes, I’m specifically talking to the two of you), both presentations have been allotted new times and locations. They are now confirmed as: New Indexing Features Introduced in Oracle 12c Release 2 (and 18c): When:  June […]

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18c Scalable Sequences Part II (Watch That Man)

In Scalable Sequences Part I, I introduced this new 18c feature (although it was hidden and undocumented in previous releases). By adding a 6 digit prefix value that constitutes the first 3 digits for the Instance Id and the next 3 digits for the Session Id, it results in a sequence value that doesn’t always […]

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“Let’s Talk Database” is Back !! Canberra/Sydney/Melbourne

Due to popular demand, I’ve been asked by Oracle to again run some “Let’s Talk Database” events this month. Dates and venues are as follows: Wednesday, 23 May – Canberra (Cliftons Canberra, 10 Moore St): Registration Link. Tuesday, 29 May – Melbourne (Oracle Melbourne Office, 417 St Kilda Road): Registration Link. Wednesday, 30 May – Sydney […]

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18c Scalable Sequences Part I (Saviour Machine)

One of the problems with populating the value of a Primary Key (or some such), is that they can cause contention, especially in relation to indexes. By having an indexed value that monotonically increases, the right-hand most index leaf block is continually being accessed, which results in a “hot block”, which in turn results in […]

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Europe June 2018 Seminars: Confirmed Venues for Munich and Zürich

I’m very excited to confirm all venues for the European June 2018 dates of my popular “Oracle Indexing Internals and Best Practices” seminar. This is a must attend seminar of benefit to not only DBAs, but also to Developers, Solution Architects and anyone else interested in designing, developing or maintaining high performance Oracle-based applications. It’s […]

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Answer: Anything Wrong With Query Performance? (Red Right Hand)

I of course attract a highly clever readership :). As some have commented, for a single table to require 1000+ consistent gets to retrieve 1000 rows implies that each row needs to be accessed from a different block. This in turn implies the Clustering Factor for this index to be relatively bad and the associated […]

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Question: Anything Wrong With Query Performance? (Straight To You)

I have a query that runs pretty darn efficiently, here’s the setup: So the query basically returns 1000 rows based on the CODE column and it does so using an index on CODE. The CBO has got the costings for this just about spot on. For 1000 rows returned, it does so with just 1006 […]

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