Using index condition; Using where; Rowid-ordered scan

Using index condition, Using where, Rowid-ordered scan are terms related to performance analysis in database queries.

1. Using index condition: This term indicates that the query is using an index to filter the rows. It means that the query is able to utilize an index to efficiently retrieve only the necessary rows based on the specified conditions. This can improve the performance of the query by reducing the number of rows that need to be scanned.

2. Using where: This term indicates that the query is using a WHERE clause to filter the rows. It means that the query is applying additional conditions to further narrow down the result set. The WHERE clause is evaluated after the initial filtering using an index condition.

3. Rowid-ordered scan: This term indicates that the rows are being scanned in the order of their physical storage on disk. It means that the database is reading the rows in the order they are stored, which can be more efficient in certain cases.

Here is an example of a query and its performance analysis:

explain select * from employees where age > 30;

Explanation:
- Using index condition: The query is using an index on the "age" column to filter the rows where the age is greater than 30.
- Using where: The query is applying an additional condition using the WHERE clause.
- Rowid-ordered scan: The rows are being scanned in the order of their physical storage on disk.