Weitzel: I would have expected some kind of predictability which could be used for optimizing the query
Keiter: Scott0_: many DBAs think they can write “faster” sql, but the engine often can rewrite it into something faster. But sometimes it fails
Correl: Scott0_: you’ll never know how it will evaluate the conditions even after you use the explain :
Correl: Scott0_: Because it does not matter how they will be evaluated
Keiter: Scott0_: the point it – don’t try to outsmart the MySQL engine
Correl: Scott0_: Just like it does not matter at all if you are evaluating these using pen an paper.
Keiter: Scott0_: you’ll waste your time, and in the few cases where the engine is wrong, you can work around it.
Keiter: Scott0_: using EXPLAIN, of course.
Correl: Scott0_: You can do it from left to right or right to left or any other way, but as long as you follow the precedence rules the end result will be always the same
Keiter: Brittman: well, if you’re at Scott0_’s skill level, anyway
Brittman: I am quite terrified of 5.7 opt hints
Correl: Scott0_: Question: Does it matter if you write: x = 2 + 1; or x = 1 + 2; ?
Keiter: Scott0_: note that I’m not saying you’re not good – just seem a bit rusty
Brittman: I wonder how many oracle apps ported to mysql with similar hints in place will just break
Correl: Scott0_: Then why did we spend so much time arguing about literally the same? :
Okelberry: Nor does it matter if its written as 2 = x -1
Keiter: Brittman: I think I have too much faith in MySQL
Correl: Scott0_: You are wrong about last one in context of SQL you know :
Stagger: X still sovles for the same
Brittman: Keiter: http://bugs.mysql.com/bug.php?id=77856
Liebig: Ahh, was just missing a ‘;’ ok works nice now
Correl: Scott0_: WHERE x = 2 + 1; is fine whereas WHERE x – 1 = 2; can be disaster
Correl: Scott0_: The latter can’t use index
Desruisseaux: I guess I was thinking mysqls engine was simpler
Correl: Scott0_: The result is the same, but the efficiency is different
Rago: Jesus its been an hour
Brittman: Yay broken logical backups during restore
Keiter: Scott0_: it’s OK, we made progress. You learned that the order doesn’t matter in the WHERE clause.
Correl: Scott0_: Here we go: http://pastie.org/10438574
Hledik: Keiter: but precedence does even though precedence is a form of order. :
Keiter: Scott0_: it isn’t. You can work on that ***umption later, too.
Asato: Its not an ***umption, it’s a definition of the word in the english language
Keiter: Scott0_: it doesn’t apply to SQL.
Vipperman: Maybe not in mysql world
Correl: Scott0_: Even better example with higher cardinality: http://pastie.org/10438575
Correl: Scott0_: Precedence in SQL is not an order. Precedence in programming languages is not an order.
Correl: Scott0_: English language doesn’t matter much when talking about terminology.
Correl: Scott0_: “operator” is a person in English in all its dictionary meaning. Not in SQL
Wygle: Https://www.google.com/search?q=define+precedence+in+programming
Crispen: Lol, they use the word order quite a bit there
Correl: Scott0_: Notably they don’t use it in a way you use it
Meiss: I said order of operations
Correl: Scott0_: Do you have MySQL related question?
Neubacher: I thought we were talking about precedence in mysql
Keiter: I think we’ve covered the subject more than adequately.
Correl: Scott0_: Do you have MySQL related question?
Strahm: And then salle threw out ” Precedence in programming languages is not an order.”