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19c

Oracle 19c: Adventures with Automatic Indexing

The video of this recent presentation, given as a part of the Oracle Groundbreakers EMEA Tour 2020, is now available.

Automatic Indexing is one of the much-heralded features of Oracle 19c, but it is only available on Engineered Systems, therefore in Autonomous Database that is built on Exadata and on other Exadata platforms. This presentation shares some initial experiences with the feature based on testing it in conjunction with Swingbench and discusses how well it performed.

Oracle 19c: Real-Time Statistics & High-Frequency Statistics Collection

The video of this recent presentation, given as a part of the Oracle Groundbreakers EMEA Tour 2020, is now available.

Keeping object statistics up to date is critical to Oracle database performance and stability. Both of these features aim to address the challenge of using data that has been significantly updated before the statistics maintenance window has run again. The features are only available on engineered systems, and so certainly are targetted at the autonomous database.

Enforcing a re-parse of a cursor in Autonomous Database. Using a hammer

While setting up a demo environment in my Autonomous Database I found that one of my tuning techniques – evicting a cursor from the shared pool – isn’t quite as straight forward as it could be. In fact, at the time of writing it wasn’t possible to force a cursor reparse in Autonomous Database (to the best of my knowledge).

The problem

Executing my flush.sql script failed, and from what I can tell, dbms_shared_pool is not exposed to users in Autonomous Transaction Processing database at the moment:

Video : Vagrant Oracle Real Application Clusters (RAC) Build

In today’s video we’ll discuss how to build a 2-node RAC setup using Vagrant.

This video is based on the OL8 19c RAC build, but it’s similar to that of the OL7 19c RAC build also. If you don’t have access to the patches from MOS, stick with the OL7 build, as it will work with the 19.3 base release. The GitHub repos are listed here.

If you need some more words to read, you can find descriptions of the builds here, as well as a beginners guide to Vagrant.

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

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)

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)

    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)

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 […]

Compression default settings

If you are loading a data warehouse or similar environment where your default approach would probably be to compress all objects because they are predominantly read only, you do not need to head back into your DDL scripts and add a “COMPRESS” clause to every table.

You can set the default compression level at the tablespace level. Here’s an example of that in action

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

  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 […]