[MySQL] piecemeal knowledge collection
Learning bits and pieces of knowledge always feels like a bear breaking sticks and forgetting one by one. Write a post and collect it, and wait until the outline is strung together.
1.limit paging optimization, 100 pages can be directly used in the simplest way, too large, you can first find out the id, and then Join associated. Pay attention to the creation of associated indexes
two。 Whether the federated index can be used under multiple conditions, for example: idx_c1_c2_c3. Where C1 > x and c2 > y and c3 > z. Then three conditions if the comparison condition contains "=", the index key of the column can be used and can be matched to the subsequent index. But if >
