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Automatic Indexing

Oracle 19c Automatic Indexing: Index Created But Not Actually Used (Because Your Young)

    The following is an interesting example of how Oracle Automatic Indexing is currently implemented that can result in an Automatic Index being created but ultimately ignored by the CBO. To illustrate, we begin by creating a simple little table that has two columns of particular interest, CODE2 which has 100 distinct values and […]

Oracle Database 19c Automatic Indexing: Minimum Number Of Required Indexes (Low)

  As I discussed in my previous posts, Oracle Automatic Indexing will try and create as few indexes as possible to satisfy existing workloads, even if that means reordering the columns in an existing index. To illustrate how Automatic Indexing creates as few indexes as possible, I’ll create the following table which has a number […]

Oracle Database 19c Automatic Indexing – Need Another Index (Another Brick in The Wall Part 2)

I previously discussed how Automatic Indexing can effectively cleverly reorder an existing index if it means it can now use the new index to satisfy new SQL predicates. In this post, we’ll explore this example further with some new workloads. So, we previously ran SQL queries with SQL predicates in the following combinations: CODE1=42 and […]

Oracle Database 19c Automatic Indexing – Indexed Column Reorder (What Shall We Do Now?)

  I previously discussed how the default column order of an Automatic Index (in the absence of other factors) is based on the Column ID, the order in which the columns are defined in the table. But what if there are “other factors” based on new workloads and the original index column order is no […]

Oracle Database 19c Automatic Indexing: Index Compression (Ghosteen)

    In my previous post on Automatic Indexing, I discussed how the default index column order (in absence of other factors) is column id, the order in which the columns are defined in the table. In this post, I’ll explore if this changes if index compression is also implemented. By default, Automatic Indexing does […]

Announcement: Australia/NZ “Let’s Talk Database” Events October 2019 !!

I’ve very excited to announce the next series of Oracle “Let’s Talk Database” events to be run throughout Australia and New Zealand in October 2019. I’ll be discussing two exciting topics this series, “Oracle Database 19c New Features” and “Oracle Exadata X8“. As always, these sessions run between 9am-1pm, include a networking lunch and are free, […]

Oracle Database 19c Automatic Indexing: Default Index Column Order Part II (Future Legend)

In Part I, we explored some options that Oracle might adopt when ordering the columns within an Automatic Index by default, in the absence of other factors where there is only the one SQL statement to be concerned with. A point worth making is that if all columns of an index are specified within SQL […]

Oracle Database 19c Automatic Indexing: Default Index Column Order Part I (Anyway Anyhow Anywhere)

The next thing I was curious about regarding Automatic Indexing was in which order would Oracle by default order the columns within an index. This can be a crucial decision with respect to the effectiveness of the index (but then again, may not be so crucial as well). Certainly one would expect the index column […]

Oracle 19c Automatic Indexing: How Many Executions Does It Take? (One Shot)

One of the first questions I asked when playing with the new Oracle Database 19c Automatic Indexing feature was how many executions of an SQL does it take for a new index to be considered? To find out, I create the following table: I then ran the following query just once and checked to see […]

Oracle 19c Automatic Indexing: My First Auto Index (Absolute Beginners)

I am SOOOO struggling with this nightmare block editor but here goes. Please excuse any formatting issues below: I thought it was time to show the new Oracle 19c Automatic Indexing feature in action and what better way than to go through how I created my first ever Automatic Index. To start, I create a […]