mariadb – determine how long the “write lock” is going to last

In a MariaDB Galera cluster composed of 3 nodes when running schema changes, for example, an ALTER and being in TOI(Total Order Isolation) mode it will write lock the full cluster until the schema upgrade finishes.

One way to prevent the global write lock is to run the upgrade in each node by doing:

SET wsrep_OSU_method='RSU';
# run the alter 
SET wsrep_OSU_method='TOI';

To find how long it has been running the query I use this:

SELECT * FROM information_schema.processlist WHERE command != 'Sleep' AND info LIKE 'alter%' AND time >= 2 ORDER BY time DESC, id LIMIT 1;

By using the file system and checking the size of the databases I can roughly get an idea in size but not time.

But in any case, how to get the progress, estimate or calculate the remaining time that the lock will last?

locking – SQL Server: When is a real shared (S, not IS) lock acquired on a page of a clustered index?

All the explanations I find seem to indicate that, without special hints – which is the case in our software -, shared locks are only acquired for keys, with IS locks at page and object level (and, yes, an S lock on the database).

Lock escalation of S row (key) locks escalates to the table (object) level, so no S page locks can result from this, if I’m correct here.

And foreign key constraint checking also gets (transaction-wide) S locks on keys, if I understand it correctly (see my other question for this).

However, we see lots of S (not IS) page locks in a simple ETL process (doing simple UPDATEs/INSERTs and some DELETEs from a connected server) – where could they come from?

Harald M.

Why didn’t Trump lock the country down in January to prevent deaths?

TLDR: I would rather have a mentally challenged homeless wino for president than I would Donald Trump…

That’s exactly right what John Hopkins says, because other medical professionals have said the same thing. Also, Countries like vietnam did exactly that; they have relatively few cases and deaths, even accounting for under reporting.

I think the answer to your question is that Trump is an arrogant person who thinks he’s special and that coronavirus would never hurt HIM or his country. Also, he knows his base; they are inclined to parrot “Liberal Fake”. Events have proved him and his hangers on Dead Wrong, wrong, wrong! LOL. three times wrong for emphasis.

recreational mathematics – Assigning keys to n people such that atleast any k people are required to open lock

Given the number of person(N) available and the number of locks(K) required to open a cell, give a specification of how to distribute the keys such that any K persons can open the locks, but no group of (k- 1) person can.


Ex-1 N=3 and k=1


Ex-2 For N=2 k=2

( (0), (1))

Ex-3 For N=3 and K=2

( (0, 1), (0, 2), (1, 2),)

Ex-4 For N=3 and k=3

( (0), (1), (2) )

Ex-5 For N=5 and k=3

((0, 1, 2, 3, 4, 5), (0, 1, 2, 6, 7, 8), (0, 3, 4, 6, 7, 9), (1, 3, 5, 6, 8, 9), (2, 4, 5, 7, 8, 9))

Error – Canon 80D – Mirror lock problem

I bought a Canon 80th. Bought last August, still under warranty. Never dropped, never exposed to high humidity / cold / heat / dust. I have always handled it with great care.

Yesterday I used it for a while to record videos. Each individual video lasted less than 10 minutes on average. Maybe a little over an hour of video recording, but the camera was on longer. I also took 3 photos (but in live view mode). Everything worked as usual. The room temperature was 24 degrees, nothing extreme.

When I tried to take a picture through the viewfinder this morning, the camera was apparently locked.
After pressing the shutter button, the image was not previewed, and then none of the controls worked. I turned it off and heard the mirror open. Turned it back on and took some photos in live view, all right.

I checked in the menu and turned off the mirror lock (I activated it in a previous session).
When the mirror lock is turned off, shooting with the viewfinder works fine.

Turning the mirror lock on caused the same problem again: shooting through the viewfinder locks the camera. When you activate the shutter, you hear a little mechanical noise, but not the complete noise that I normally hear. After restarting the camera, I checked if the picture was taken. It didn't.

I used mirror locking a few times before and it always worked well.

What I want to ask is: should I check other settings that explain this behavior or should I just contact Canon Maintenance Service to fix the problem?

Thanks a lot

Lock screens – my phone is unlocked but i can't remember the PIN code. Recover from Google somehow?

There are many instructions for those who forget their PIN code and cannot unlock their phone, but there is no explanation for those who have unlocked their phone but do not remember their PIN code to change it.

I can use my phone now, but I don't remember my PIN. That is why once it is turned off or the screen is locked, which will happen at night, I may not be able to access it without erasing the data.

Is there an easier way for me to deal with the problem?

Astrophotography – Shutter Lock Sony A6500

I saw a video of astro photography.

In this video, he automatically took pictures of the night sky every 30 seconds with a shutter speed of 30 seconds and then combined all of these pictures into a star circle.

I was wondering what those operations are called.

1] so that my sony a6500 takes pictures every 30 seconds = time lapse?

2] If I want the camera to take a picture every 30 seconds = ael mode of 30 seconds?

Sorry if I combined terms. I'm fairly new and trying to understand how to make this process of combining the photos into a circular pattern.

Thank you so much!

Uninstall – The lock screen has not been reset

I installed the Ubuntu Budgie desktop environment, I really liked it, but I like the original Ubuntu desktop environment more. I tried to uninstall the budgie with the following command:

sudo apt remove ubuntu-budgie-desktop ubuntu-budgie* lightdm

sudo apt autoremove

sudo apt install --reinstall gdm3

After that, the desktop switched back normally, but the lock screen didn't switch back to the original.

Terminal Coomands

Can somebody help me with it?