2012/12/28 Vitalii Tymchyshyn <tivv00@xxxxxxxxx>: > Why so? Basic form "case lvalue when rvalue then out ... end" is much like > switch. > The "case when condition then out ... end" is different, more complex beast, > but first one is essentially a switch. If it is now trnasformed into > "case when lvalue = rvalue1 then out1 when lvalue=rvalue2 then out2 ... end" > then this can be optimized and this would benefit many users, not only ones > that use partitioning. please, look to plpgsql source code. PL/pgSQL is too simply and has not own arithmetic unit - all is transformed to SELECTs, has not any optimization. But is really short and maintainable. These SELECTs are evaluated only when it is necessary - but it is evaluated by PostgreSQL expression executor - not by PL/pgSQL directly - PL/pgSQL cannot process constant by self. So any enhancing needs PL/pgSQL redesign and I am not sure, so this use case has accurate benefit, because expression bottleneck is only one part of partitioning triggers bottleneck. More - if you need really fast code, you can use own code in C - and it be 10x times faster than any optimized PL/pgSQL code. And using C triggers in PostgreSQL is not terrible work. Using plpgsql row triggers for partitioning is not good idea - it is just work around from my perspective, and we should to solve source of problem - missing native support. Regards Pavel Stehule > > > 2012/12/28 Stephen Frost <sfrost@xxxxxxxxxxx> >> >> Vitalii, >> >> * Vitalii Tymchyshyn (tivv00@xxxxxxxxx) wrote: >> > There is switch-like sql case: >> [...] >> > It should work like C switch statement. >> >> It does and it doesn't. It behaves generally like a C switch statement, >> but is much more flexible and therefore can't be optimized like a C >> switch statement can be. >> >> Thanks, >> >> Stephen > > > > > -- > Best regards, > Vitalii Tymchyshyn -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
