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Focusing Specifically On Oracle Indexes, Database Administration and Some Great Music
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Oracle 19c Automatic Indexing: Non-Equality Predicates Part I (Lucy Can’t Dance)

Thu, 01/14/2021 - 06:43
  I’ve been waiting a while before posting a series on the various limitations associated with Automatic Indexing, in order to see how the feature matures over time. The following have all been re-tested post 1 January 2021 on the Autonomous ATP Database Cloud service, using Oracle Database version 19.5.0.0.0. In the Oracle Documentation (including […]

Oracle 19c Automatic Indexing: Indexing Partitioned Tables Part II (Neighbourhood Threat)

Wed, 01/13/2021 - 06:38
In my first post on Automatic Indexing on Partitioned Tables, I discussed how Automatic Indexing (AI) can now create a Non-Partitioned index if deemed the most effective indexing structure (this wasn’t supported when AI was initially released). A Non-Partitioned index is indeed likely the most efficient indexing structure if the underlying table has many partitions […]

Oracle 19c Automatic Indexing: Currently Broken In Autonomous ATP Databases Part II (Fix You)

Tue, 01/12/2021 - 00:43
  Firstly, thank you for all those who contacted me regarding the issue with Oracle Automatic Indexing (AI) having stopped working within the Autonomous ATP Database Cloud service. It appears this issue was indeed widely spread and impacted numerous (if not all) Autonomous ATP Database Cloud services. This was all possibly due to (unpublished) bug […]

Oracle 19c Automatic Indexing: Currently Broken In Autonomous ATP Databases? (What In The World)

Thu, 12/17/2020 - 06:24
  I’ve been playing with the free tier Oracle Autonomous Databases for quite some time, but unfortunately in recent times, I’ve hit a bit of a snag. The Automatic Index capability appears to be currently broken… The Automatic Indexing task appears to have stopped running, yes even with the AUTO_INDEX_MODE set to “IMPLEMENT” and with […]

Announcement: New Oracle Webinars Scheduled For February 2021 !!

Mon, 11/23/2020 - 04:46
  After much badgering from a number of you (you know who you all are), I’m pleased to finally announce the scheduling of 2 new webinars for February 2021 !! As usual, places are very strictly limited as I only run small classes to give every attendee the opportunity to get the most from the […]

Oracle 19c Automatic Indexing: Indexing Partitioned Tables Part I (Conversation Piece)

Wed, 10/14/2020 - 04:47
In this little series, I’m going to discuss how Automatic Indexing works in relation to Partitioning. I’ve discussed Indexing and Partitioning many times previously and how Oracle has various options when indexing a partitioned table: Non-Partitioned Index Globally Partitioned Index Locally Partitioned Index So the question(s) are how does Automatic Indexing handle scenarios with partitioned […]

Oracle 19c Automatic Indexing: Indexing With Stale Statistics Part III (Do Anything You Say)

Thu, 10/08/2020 - 04:22
In Part I of this series, we saw how Automatic Indexing will not create a viable Automatic Index if there are stale or missing statistics on the underlining segments. In Part II we saw how these SQL statements effectively become blacklisted and when segment statistics are subsequently collected, Automatic Indexing will still not create viable […]

Oracle 19c Automatic Indexing: Indexing With Stale Statistics Part II (Survive)

Wed, 10/07/2020 - 06:07
    In my previous post, I discussed how having stale statistics, usually a bad idea, is especially problematic with regard Automatic Indexes as it usually results in viable automatic indexes only being created in an UNUSABLE/INVISIBLE state. If we were to now to collect the missing statistics:   If we now repeatedly re-run the […]

Oracle 19c Automatic Indexing: Indexing With Stale Statistics Part I (Dead Against It)

Tue, 10/06/2020 - 04:56
A “golden rule” when working with Automatic Indexing is that things don’t work properly if there are stale statistics on the dependant objects. Stale statistics can of course be problematic but they can be particularly troublesome when dealing with Automatic Indexing. In the Oracle Autonomous Database environments, this issue is addressed somewhat by the new […]

Oracle 19c Automatic Indexing: Data Skew Fixed By Baselines Part II (Sound And Vision)

Mon, 09/28/2020 - 06:00
  In my previous post, I discussed how the Automatic Indexing task by using Dynamic Sampling Level=11 can correctly determine the correct query cardinality estimates and assume the CBO will likewise determine the correct cardinality estimate and NOT use an index if it would cause performance to regress. However, if other database sessions DON’T use […]

Oracle 19c Automatic Indexing: Data Skew Fixed By Baselines Part I (The Prettiest Star))

Fri, 09/25/2020 - 01:53
In my previous few blog posts, I’ve been discussing some issues in relation to how Automatic Indexes handle SQL statements that accesses skewed data. In this post, I’m going to setup the scenario in which Automatic Indexing can potentially use Baselines to help address some of these issues. BUT, as we’ll see, I’m having to […]