Database developer, data engineer, Oracle Ace Pro β Born in Ukraine Views are my own
Joined November 2017
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#JoelKallmanDay
#Oracle26ai introduces QUALIFY β a welcome addition to Oracle SQL that makes filtering on analytic function results much easier.
But what happens under the hood? Query transformations and execution plans reveal a few surprises.
blog.sqlora.com/en/oracle-26β¦
A very good question on my first Oracle 26ai JOIN TO ONE post made me look even closer.
This time: the real CBO transformations behind the implicit LEFT OUTER JOIN β and the performance impact of the runtime checks.
blog.sqlora.com/en/oracle-26β¦
#Oracle26ai #SQL
A few months ago, Oracle 26ai introduced the new JOIN TO ONE syntax. After a first look during one of my Oracle 26ai trainings, I wanted to explore it further from a data warehouse perspective.
Thoughts and experiments:
blog.sqlora.com/en/oracle-26β¦
#Oracle26ai #SQL #DataWarehouse
A few months ago, Oracle 26ai introduced the new JOIN TO ONE syntax. After a first look during one of my Oracle 26ai trainings, I wanted to explore it further from a data warehouse perspective.
Thoughts and experiments:
blog.sqlora.com/en/oracle-26β¦
#Oracle26ai #SQL #DataWarehouse
Andrej Pashchenko πΊπ¦ ππ retweeted
With online stats gathering, Oracle AI Database captures stats when you use
CREATE TABLE AS SELECT
A direct path INSERT INTO ... SELECT into an empty table
@Andrej_SQL investigates its evolution
And finds many restrictions are lifted 26ai
blog.sqlora.com/en/online-stβ¦
Andrej Pashchenko πΊπ¦ ππ retweeted
ππ» MakeIT 2026 & JCON Slovenia 2026 are almost here!
Join the Oracle, Java, and open-source community in PortoroΕΎ, Slovenia for three exciting days of learning, innovation, and networking. π
Weβre excited to see Oracle ACEs sharing their expertise and connecting with the international tech community throughout the conference!
π PortoroΕΎ, Slovenia | π
May 27β29, 2026
π social.ora.cl/6019BBSYwz
Looking forward to inspiring sessions, hands-on workshops, and amazing community energy by the Adriatic coast! π
@AndrevanderPut @Andrej_SQL @danischnider @erikvanroon @gianniceresa @gilsonsm @kamil_stawiars @LucasJellema @MarcinDBA @thecodergal @commi235 @ChandlerDBA @patrickjollif1 @PetarSimic @rhjmartens @RustamMehmand1 @uzhnik @ziga_vaupot @zorantica @OyvindIsene
#OracleACE
Andrej Pashchenko πΊπ¦ ππ retweeted
π£ HrOUG & JavaCro 2026 Call for Speakers is open!
Submit your talk or workshop and share your experience with the IT community.
π Mar 1 β May 31, 2026
π Rovinj, Croatia
π HrOUG: 2026.hroug.hr/eng/Call-for-pβ¦
π JavaCro: 2026.javacro.hr/eng/Call-forβ¦
#Java #Oracle #TechCommunity
New short blog series on Oracle 26ai CALENDAR functions. Part 2: execution context and the question β Do I still need a time dimension?
#Oracle #SQL #26ai #DataWarehouse blog.sqlora.com/en/calendar-β¦
New short blog series on Oracle 26ai CALENDAR functions.
Part 1: semantics and implementation nuances.
#Oracle #SQL #26ai
blog.sqlora.com/en/calendar-β¦
Andrej Pashchenko πΊπ¦ ππ retweeted
Storing UUIDs as RAW values is more efficient than strings
But RAW can lead to implicit conversions => poor row estimates
If you're stuck with string comparisons @Andrej_SQL shows how to improve row estimates with
Extended stats
Virtual columns
blog.sqlora.com/en/fix-optimβ¦
New post for #JoelKallmanDay!
Ever wondered why the Oracle Optimizer sometimes ignores your histograms? Implicit data type conversions might be to blame. Hereβs how to fix it without touching your SQL and with minimal schema impact.
#Oracledatabase
blog.sqlora.com/en/fix-optimβ¦
Honored to speak at #HROUG2025 β celebrating its 30th anniversary in amazing Rovinj!πHuge thanks to the organizers for keeping this fantastic community going for 30 years!π
Letβs put some old SQL myths to the test together! #Oracle #SQL #Optimizer #Accenture #OracleAce
MERGE ... RETURNING is now supported in #Oracle23ai. In my view, it deserves more visibility in the documentation β it wasnβt easy to find. Even LLMs still claim it doesnβt exist (some even invent error codes). #SQL #MERGE @oracleace
blog.sqlora.com/en/merge-andβ¦
Ten years after my first post on the quirks of MERGE and ORA-30926, I took a fresh look at how Oracle 23ai handles it. Clearer error messages, improved diagnostics, and fewer unnecessary restarts. Read the new blog post
#Oracle23ai #SQL #MERGE @oracleace
blog.sqlora.com/en/ora-30926β¦
Did you know that refreshing HCC-compressed materialized views with atomic_refresh=true can multiply storage usage over time? Small details can have massive impacts. Read the new blog post.
#Exadata #Oracle #HCC
@oracleace
blog.sqlora.com/en/when-compβ¦
Andrej Pashchenko πΊπ¦ ππ retweeted
Get rows in one table with no match in another with either
c1 NOT IN ( SELECT c2 ... )
NOT EXISTS ( SELECT ... where c1 = c2 )
These perform the same in Oracle #SQL
...unless C2 includes NULL values => NOT IN returns no rows!
@Andrej_SQL explores blog.sqlora.com/en/not-in-vsβ¦
ALT The execution plans for NOT EXISTS and NOT IN queries. In both cases the Oracle optimizer is able to transform them into a null aware anti join
Andrej Pashchenko πΊπ¦ ππ retweeted
My @AccentureDACH colleague @Andrej_SQL is going to talk about partition exhange at the @Hroug_Croatia #HROUG2024 conference
@oracleace
Andrej Pashchenko πΊπ¦ ππ retweeted
Partition Exchange Reloaded by @Andrej_SQL at #hroug2024.
Everything you should know about block corruptions in #Oracledatabase with @CGohmannDE at #hroug2024
On this #JoelKallmanDay, I would like to follow up on my last year's post, comparing #SQLβs NOT IN and NOT EXISTS, focusing on their usage, interchangeability and some myths about performance differences.
blog.sqlora.com/en/not-in-vsβ¦
#Oracledatabase
And if you want to use your existing views and let SQL macros "inject" parameter, you can check the second part (blog.sqlora.com/en/parameterβ¦) of this post and also @StewAshton 's post: stewashton.wordpress.com/202β¦
Views are great for creating reusable #SQL statements
But they have a drawback: you can't pass parameters to them!
@Andrej_SQ shows how to emulate these with SQL macros in Oracle Database
Use these to create parameterized query templates
blog.sqlora.com/en/parameterβ¦
ALT Examples calling the SQL macro time_machine.vw, passing different tables and date parameters