Andrej Pashchenko 🇺🇦 💙💛

Database developer, data engineer, Oracle Ace Pro ♠
Born in Ukraine
Views are my own

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

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 — and the performance impact of the runtime checks.

https://t.co/WnnVUwPaDr

#Oracle26ai #SQL

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_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:
https://t.co/7fdU55115x
#Oracle26ai #SQL #DataWarehouse

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_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:
https://t.co/7fdU55115x
#Oracle26ai #SQL #DataWarehouse

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

@ruedibosshart @SchullerKonrad Im Original ist eben "stöhnen"

[SQL Daily @sqldaily]

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

https://t.co/YJiqzYFmRF

[Oracle ACE Program @oracleace]

🌊💻 MakeIT 2026 & JCON Slovenia 2026 are almost here!

Join the Oracle, Java, and open-source community in Portorož, Slovenia for three exciting days of learning, innovation, and networking. 🚀

We’re excited to see Oracle ACEs sharing their expertise and connecting with the international tech community throughout the conference!

📍 Portorož, Slovenia | 📅 May 27–29, 2026
🔗 https://t.co/kTh4pXjoGy

Looking forward to inspiring sessions, hands-on workshops, and amazing community energy by the Adriatic coast! 🙌
@AndrevanderPut @Andrej_SQL @danischnider @erikvanroon @gianniceresa @gilsonsm @kamil_stawiars @LucasJellema @MarcinDBA @thecodergal @commi235 @ChandlerDBA @patrickjollif1 @PetarSimic @rhjmartens @RustamMehmand1 @uzhnik @ziga_vaupot @zorantica @OyvindIsene
#OracleACE

[Davor Ranković @Davorranko]

📣 HrOUG & JavaCro 2026 Call for Speakers is open!
Submit your talk or workshop and share your experience with the IT community.

🗓 Mar 1 – May 31, 2026
📍 Rovinj, Croatia

🔗 HrOUG: https://t.co/TEeA7H0gJP
🔗 JavaCro: https://t.co/gqL5xaN0A8

#Java #Oracle #TechCommunity

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

New short blog series on Oracle 26ai CALENDAR functions. Part 2: execution context and the question — Do I still need a time dimension?
#Oracle #SQL #26ai #DataWarehouse https://t.co/T5c7vP1Yrc

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

New short blog series on Oracle 26ai CALENDAR functions.
Part 1: semantics and implementation nuances.
#Oracle #SQL #26ai
https://t.co/qSnW12r1VX

[SQL Daily @sqldaily]

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

https://t.co/9SPPa3NhmG

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

New post for #JoelKallmanDay!
Ever wondered why the Oracle Optimizer sometimes ignores your histograms? Implicit data type conversions might be to blame. Here’s how to fix it without touching your SQL and with minimal schema impact.
#Oracledatabase
https://t.co/DkqCeAAqWc

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

Honored to speak at #HROUG2025 – celebrating its 30th anniversary in amazing Rovinj!🎉Huge thanks to the organizers for keeping this fantastic community going for 30 years!🙏
Let’s put some old SQL myths to the test together! #Oracle #SQL #Optimizer #Accenture #OracleAce

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

@MartinDBA @oracleace Yes, but the focus in New Features docs has shifted to old/new enhancements, almost ignoring that RETURNING was not available for MERGE before 23ai. At least in my perception.

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

MERGE ... RETURNING is now supported in #Oracle23ai. In my view, it deserves more visibility in the documentation — it wasn’t easy to find. Even LLMs still claim it doesn’t exist (some even invent error codes). #SQL #MERGE @oracleace
https://t.co/FpbYdL2oDS

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

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
https://t.co/13xIIS7cIk

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

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
https://t.co/sPsa6z6CPQ

[SQL Daily @sqldaily]

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 https://t.co/VGVFCcWMUS

[Christian Gohmann @CGohmannDE]

My @AccentureDACH colleague @Andrej_SQL is going to talk about partition exhange at the @Hroug_Croatia #HROUG2024 conference

@oracleace

[Philipp Salvisberg @phsalvisberg]

Partition Exchange Reloaded by @Andrej_SQL at #hroug2024.

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

Everything you should know about block corruptions in #Oracledatabase with @CGohmannDE at #hroug2024

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

@dani_schnider talking about the intelligence of #SQL Analysis report in #Oracle23ai at #hroug2024 in Rovinj
@oracleace