Where is the cf coming from? And what is the chosen plan for each of
these queries? I don't know of any general way to arrange queries, but
looking at the plan often suggests how things can be improved.

Set

--- In firebird-support@yahoogroups.com, "kimon_the_athenian2" wrote:
> 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