Hi!

I noticed a huge difference of query speed when i switched table2 and
table3 joins in FROM clause from:

select t1.stuff, t2.stuff, t3.stuff
from table1 t1
join table2 t2 on t2.id = t1.field4
left join table3 t3 on t3.field1 = cf.field1 and t3.field2 = cf.field2
where t1.field1 = :p1
and t1.field2 = :p2
and t1.field3 = :p3

to:

select t1.stuff, t2.stuff, t3.stuff
from table1 t1
left join table3 t3 on t3.field1 = cf.field1 and t3.field2 = cf.field2
join table2 t2 on t2.id = t1.field4
where t1.field1 = :p1
and t1.field2 = :p2
and t1.field3 = :p3

First query run for 10 mins, the second for 2 secs (FB 1.5.2).

As far as I understand swithcing these joins should always give
equivivalent result set, is it so?

Somehow it feels more logical to me to put all inner joins before
left ones, but seems that I need to reconsider this :)

Is there some text describing how should I arrange joins?

thanks in advance!

Aivar