1. Why use B+ trees instead of other structures?
Hash indexes are stored in Hash format and are fast to search for columns. Range search is not supported
The worst case of binary tree is linear structure, increase I/O times
Balanced binary tree (AVL) :
The layer height is relatively high, increase I/O times
AVL definition: The absolute value of height difference between the left and right subtrees of the root node is less than 1. The left and right subtrees of any node are AVL trees
B tree
B tree stores data on both leaf and non-leaf nodes. As a result, the number of Pointers that can be saved on non-leaf nodes decreases. If the number of Pointers is small, the height of the tree can only be increased to save a large amount of data, resulting in more I/O operations and lower query performance
B + tree
Multi-path lookup trees can reduce the height of the tree, can be batched to memory, data is in leaf nodes, and range data is not accessed across layers
Refer to www.liuzk.com/410.html
2. By what means is ACID guaranteed?
3. Explain the meaning of each parameter?