Timeline for 19c database suddenly using CBO on a certain query
Current License: CC BY-SA 4.0
7 events
| when toggle format | what | by | license | comment | |
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| Oct 27, 2023 at 16:31 | comment | added | Andrew Sayer | The bug note is very specific but it the actual issue is generic and happens when a standby turns into a primary. I raised a case identical to yours and Oracle support linked it with this one. | |
| Oct 27, 2023 at 8:23 | comment | added | Carlovski | Interesting, the bug explicitly states when optimizer_mode=first_rows, which isn't the case here. And it wasn't a snapshot standby. It does sound like we might have some variation on the bug though. Will try the hint today, and we are planning to fail back over next week which might just fix it too. | |
| Oct 27, 2023 at 8:19 | comment | added | Carlovski | I just meant the dev cloned the app so we can have a play with it without impacting anyone (As we can't replicate this in a non-prod environment). | |
| Oct 26, 2023 at 17:57 | comment | added | Andrew Sayer | Bug is 30572816 (although could be additional ones). Sounds like you’d be best off getting a hint in someway for now (if it’s APEX then should be relatively trivial but a SQL Patch is a decent last option). I’m not sure what you mean by mirrored copy, but you should be able to replicate the bug by doing a DG switchover so make sure that’s involved in your testing. | |
| Oct 26, 2023 at 8:34 | comment | added | Carlovski | Thanks - any idea on the bug ID? I couldn't find anything when I looked.. We are on 19.8 - so yeah quite a few patch releases behind. Getting downtime for a restart is tricky (It's a hospital...), though we will have some for the switchback we will be doing soon. I can try the patch (Or we can update the app, I've got a mirrored copy I can play with first anyway), or I can try forcing the good plan. | |
| Oct 25, 2023 at 4:26 | history | edited | Andrew Sayer | CC BY-SA 4.0 |
added 349 characters in body
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| Oct 25, 2023 at 2:40 | history | answered | Andrew Sayer | CC BY-SA 4.0 |