Server change number
Imagine you have a toy box filled with different types of toys like cars, dolls, and building blocks. Let's say you have a rule that says you can only take out one toy at a time and you always have to put it back before taking out another toy.
Now, let's say you have a friend who also has a toy box like yours, but with different types of toys. If you both want to play with each other's toys, you would have to agree on a way to keep track of which toys are being played with, so you don't accidentally take out the same toy at the same time.
The server change number is like a special number that helps different servers (or toy boxes) keep track of which toys (or data) are being used at the same time. It's like a signal that tells the servers if it's okay to make changes or if they need to wait until the other server is done.
Just like how you and your friend need to communicate and agree on the toy sharing rules, servers need to communicate and agree on the server change number rules to make sure everything runs smoothly.
Now, let's say you have a friend who also has a toy box like yours, but with different types of toys. If you both want to play with each other's toys, you would have to agree on a way to keep track of which toys are being played with, so you don't accidentally take out the same toy at the same time.
The server change number is like a special number that helps different servers (or toy boxes) keep track of which toys (or data) are being used at the same time. It's like a signal that tells the servers if it's okay to make changes or if they need to wait until the other server is done.
Just like how you and your friend need to communicate and agree on the toy sharing rules, servers need to communicate and agree on the server change number rules to make sure everything runs smoothly.