Execution plans are tricky and reading them accurately to make good decisions require a lot of experience and awareness of the situation. It does not only require that you know how to read the tool itself but also know how the DB and schemas have been designed, if stats are up to date, how tables are populated, frequency and type of queries, adequate indexing in place, the hardware it sits on, etc.
It's a mix of science, broaden knowledge, perspicacity, and why not say, it's an art.
I read this nice article about Understanding EXPLAIN [1] weeks ago that opened my mind about the tool, but it seems no enough to explain a lot of plans that I see in this list.
Thanks.
I often read responses to a plan that are not covered by the article.
I need/want to know EXPLAIN better.
Can you kindly advise me a good reading about advanced EXPLAIN?
There's not much out there. This document was written after reading this list, viewing some talks (you may find a lot of them on youtube), and reading the code.
I intend to update this document, since I learned quite more since 2012. Though I didn't find the time yet :-/
Anyway, thanks.
Hello all
I would like to make clear that there are two "Flavio Henrique" on the lists, me beeing one of them, I'd like to say that I'm not the OP.