https://blog.ora-600.pl/Field notes from the ORA-600 labhttps://blog.ora-600.pl/2026/07/13/nls_territory-and-weird-reason-in-vsql_shared_cursor/https://blog.ora-600.pl/2026/07/13/nls_territory-and-weird-reason-in-vsql_shared_cursor/Mon, 13 Jul 2026 15:24:15 GMTOne of my customers experienced a weird behavior – thousands of child cursors with LANGUAGE_MISMATCH When I looked closer, into V$SQL_SHARED_CURSOR.REASON I saw something puzzling: While this part is normal: Behttps://blog.ora-600.pl/2025/10/13/noisy-neighbors-oracle-latches-and-multitenant/https://blog.ora-600.pl/2025/10/13/noisy-neighbors-oracle-latches-and-multitenant/Mon, 13 Oct 2025 11:47:19 GMTA year ago I described the basics of checkpoint queue latches: After writing that article, I attended an excellent lecture by Mike Dietrich and Daniel Overby Hansen about noisy neighbors in a multitenant envirohttps://blog.ora-600.pl/2025/07/28/jas-min-and-ai/https://blog.ora-600.pl/2025/07/28/jas-min-and-ai/Mon, 28 Jul 2025 10:49:53 GMTI know, I know – AI is stupid… but we shouldn’t be and LLM is a tool that we should get familiar with. That’s why JAS-MIN gets integration with AI in two modes – one-time batch processing and backend assistant.https://blog.ora-600.pl/2025/04/12/simulate-oracle-cloud-on-kvm-olvm/https://blog.ora-600.pl/2025/04/12/simulate-oracle-cloud-on-kvm-olvm/Sat, 12 Apr 2025 13:59:15 GMTWe have no idea when Oracle 23ai will be released on premises. And it is a shame, since this database is offering a lot of great features that you probably would like to learn! One of the solutions is to use Orhttps://blog.ora-600.pl/2025/02/20/rico3-as-a-tool-for-thief/https://blog.ora-600.pl/2025/02/20/rico3-as-a-tool-for-thief/Thu, 20 Feb 2025 19:41:56 GMTI know I know, it’s getting boring when I constantly talk and write about an evil KVM admin, but tomorrow starts our first meetup with IBM and they are going to explain why my hacks won’t work in Power environmhttps://blog.ora-600.pl/2024/12/13/jas-min/https://blog.ora-600.pl/2024/12/13/jas-min/Fri, 13 Dec 2024 10:58:49 GMTNot having Diagnostic Pack sucks. But event if you have it, it is not that obvious that you will be able to visualize properly the data and perform a meaningful analyze. That’s why I have created JAS-MIN! A lithttps://blog.ora-600.pl/2024/08/02/when-security-drives-you-crazy-cbfuk/https://blog.ora-600.pl/2024/08/02/when-security-drives-you-crazy-cbfuk/Fri, 02 Aug 2024 11:16:46 GMTMore and more customers are using fancy security tools like CyberArk or other solutions based on Windows RDP with turned off or limited possibility of copy/paste functionalities. And I get it. Security is reallhttps://blog.ora-600.pl/2024/06/11/how-checkpoint-queue-actually-works-the-basic-scenario/https://blog.ora-600.pl/2024/06/11/how-checkpoint-queue-actually-works-the-basic-scenario/Tue, 11 Jun 2024 20:38:03 GMTThis article is true for Oracle 19.19 and 19.23 on ARM. On x86_64 there’s something funny going on with location of the buffer address in the private memory (finding appropriate register at kcbklbc call)- I neehttps://blog.ora-600.pl/2024/02/10/solved-ora-39405-oracle-data-pump-does-not-support-importing-from-a-source-database-with-tstz/https://blog.ora-600.pl/2024/02/10/solved-ora-39405-oracle-data-pump-does-not-support-importing-from-a-source-database-with-tstz/Sat, 10 Feb 2024 19:11:58 GMTThis is a pain in the ass. You try to import something from a newer database and you hit the error that your timestamp is not good enough! Even tho you have no timestamp datatypes in the dump… The whole case wahttps://blog.ora-600.pl/2023/09/18/binary-patching-hacking-vm-process/https://blog.ora-600.pl/2023/09/18/binary-patching-hacking-vm-process/Mon, 18 Sep 2023 10:55:53 GMTWe are continuing our journey as an evil KVM administrator who wants to mess with a tenants virtual machines. This time we will modify a binary execution code path by changing machine code opcodes in a running https://blog.ora-600.pl/2023/09/04/last-resort-data-recovery/https://blog.ora-600.pl/2023/09/04/last-resort-data-recovery/Mon, 04 Sep 2023 09:07:02 GMTShit happens. We had recently another customer who can relate to that absolute truth – after a serious storage problem, they managed to restore only data files from one mount point. In theory they were lucky behttps://blog.ora-600.pl/2023/05/24/hacking-database-writer/https://blog.ora-600.pl/2023/05/24/hacking-database-writer/Wed, 24 May 2023 08:45:39 GMTSo we continue our journey to understand the nature of buffer cache and forcing DBWR process to write our changes to disk. If you want to follow this thread – you should get familiar with at least those blog pohttps://blog.ora-600.pl/2023/03/03/flashback-query-and-cursor-pin-s-wait-on-x/https://blog.ora-600.pl/2023/03/03/flashback-query-and-cursor-pin-s-wait-on-x/Fri, 03 Mar 2023 11:35:14 GMTCheck out those charts: During my last performance tuning audit I found out that database is consuming big amounts of CPU on parsing. One of the queries that took significant amount of time was rather a small Dhttps://blog.ora-600.pl/2022/12/23/blockrecover-in-standard-edition-nope-but-close-enough/https://blog.ora-600.pl/2022/12/23/blockrecover-in-standard-edition-nope-but-close-enough/Fri, 23 Dec 2022 12:27:50 GMTHalloween started really scary this year – some company called us and said, that they have some problems with their Oracle Database Standard Edition. Apparently they had a storage crash six months before, whichhttps://blog.ora-600.pl/2022/10/02/how-to-change-root-password-of-running-vm/https://blog.ora-600.pl/2022/10/02/how-to-change-root-password-of-running-vm/Sun, 02 Oct 2022 14:06:46 GMTYou may already read my articles about virtualization/cloud security: In the above articles I was impersonating an evil cloud administrator and showing you how this kind of person can access and modify even enchttps://blog.ora-600.pl/2022/05/19/rss-memory-oracle-and-hugepages/https://blog.ora-600.pl/2022/05/19/rss-memory-oracle-and-hugepages/Thu, 19 May 2022 15:08:02 GMTRecently a customer called us that there is something wrong after upgrading Oracle Database to 19.15 on RedHat. Apparently The amount of RAM consumed by DBWR and process servers became really impressive – as a https://blog.ora-600.pl/2022/05/13/oracle-rac-21c-restore-ocr-and-votedisk/https://blog.ora-600.pl/2022/05/13/oracle-rac-21c-restore-ocr-and-votedisk/Fri, 13 May 2022 09:02:17 GMTSix years ago I wrote a short instruction on how to restore OCR and Votedisk in RAC 12c after a diskgroup failure. Yesterday I had a possibility of validating my procedure in 21c RAC environment and it has occuhttps://blog.ora-600.pl/2022/02/14/attacking-encrypted-blocks-by-cloud-admin/https://blog.ora-600.pl/2022/02/14/attacking-encrypted-blocks-by-cloud-admin/Mon, 14 Feb 2022 16:28:15 GMTSo you have migrated your databases to cloud and you want to feel a bit more secure – what do you do? Of course you follow the golden rule and you encrypt you tablespaces. That’s reasonable and that’s what vendhttps://blog.ora-600.pl/2021/05/07/rust-as-oracle-external-procedure/https://blog.ora-600.pl/2021/05/07/rust-as-oracle-external-procedure/Fri, 07 May 2021 12:23:55 GMTInspired by a little chat with Frits Hoogland about the future of programming languages I challenged myself to learn a bit of Rust and show how to create a shared library to send emails and attach it to Oracle https://blog.ora-600.pl/2021/05/04/golang-as-oracle-external-procedure/https://blog.ora-600.pl/2021/05/04/golang-as-oracle-external-procedure/Tue, 04 May 2021 17:30:18 GMTThis short article is a result of the following Twitter activity: So let’s do it! First of all, you have to install GoLang: https://golang.org/doc/install Once this is done, we can create a Go program to send e