| Won't forbid to use join if the joined tables are more than three and business needed. Columns to be joined MUST be with absolutely same data types. And make sure that columns to be joined are indexed | Recommend | |
| The last columns of ORDER BY clauses should be at the end of a composite index. | Recommend | MySQL has this requirement and we need to check if PostgreSQL has same requirement as well. |
| Make use of Covering Index for query to avoid additional query after searching index. | Recommend | MySQL has such a situation and we need to check if PostgreSQL has same situation. |
| The target of SQL performance optimization should AVOID these result types of EXPLAIN. | Recommend | We need to take care if we will need to use index for related columns which exist implicit type conversion. |
