Database Query Tuning

1. SELECT clause

In sufficient cases, you can select only columns with indexes that are very fast

If unnecessary, selecting only the columns you want to view will increase your speed.

2. FROM clause

When you use join, you can directly join the table, and if the join subquery, the temporary table generated by the subquery is not indexed, so it can cause slow speed, and the direct join table can increase the speed.

Use different joins depending on the situation to increase the speed of queries and statistics

3. WHERE clause

Conditions in the WHERE clause:

Add an index of type btree if you need to sort, whether unique or not

If it is a unique value and does not require sorting, add a unique hash index

If it is not a unique value and does not require sorting, and if there are not many duplicate values, you can add a hash index

4. ORDER BY clause

By conditions it is best to add Btree index

　　

Database Query Tuning