Andrej Pashchenko 🇺🇦 💙💛

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

[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

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

On this #JoelKallmanDay, I would like to follow up on my last year's post, comparing #SQL’s NOT IN and NOT EXISTS, focusing on their usage, interchangeability and some myths about performance differences.
https://t.co/Vhxo8nRPgQ
#Oracledatabase

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

And if you want to use your existing views and let SQL macros "inject" parameter, you can check the second part (https://t.co/C8oITOekFk) of this post and also @StewAshton 's post: https://t.co/gXXuGRao6u

[SQL Daily @sqldaily]

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

https://t.co/oXL1p6Y1Zr

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

I am absolutely thrilled to be presenting at the #HROUG2024 for the first time. Thanks @Hroug_Croatia for accepting my talks. In just two weeks! See you there!
@oracleace

[Andrej Pashchenko 🇺🇦 💙💛 @Andrej_SQL]

There have been some changes and improvements to the Online Statistics Gathering for Bulk Loads over the last few years. Here is the new blog post:
#oracledatabase
@oracleace

https://t.co/YxVA8ueOYt