Re: Composite index - selecting components and order

[Rick James]

> Are you saying that composite indexes with more than one item in them are a bad thing?

No, not saying composite indexes would be bad.
Rather, I am saying they may not be beneficial for that SELECT.

> I was of the impression that you wanted many items from your WHERE clause,

Many items that are tested via "=", then one more item.

> in the order they appear in the WHERE, for optimum performance

The order in the WHERE clause is irrelevant.

Max/min requires a GROUP BY (unless you just want a max/min over the whole table).

The ORDER BY may be useful after the GROUP BY.

The syntax of the SELECT statement mirrors the order in which the operations are done:
WHERE (filtering)
GROUP BY (to trigger aggregation)
HAVING (kinda like a WHERE for aggregations)
ORDER BY (sorting the final result)
LIMIT (stopping short)

> The suggestion that indexes should only have 2 items in them would make for totally different schema design choices.

I don't understand what you are saying there. The SELECT determines what indexes would be useful.