----- "Christoph Handel" <[EMAIL PROTECTED]> escribió: > load_balance_mode -> Selects will be distributed to all nodes. So > first query going to node 1, next query to to node 2, ... > > replicate_select -> if set to true all selects will be executed on > all > nodes? How does this work with load_balance_mode?
As far as I know, replicate_select allows you detect data mismatch. But I am not sure about this feature either, and would like Tatsuo to tell us the difference about it, too :) > With: > > load_balance_mode = true > replicate_select = false > > Selects will be distributed? Right? Yes. > With > > load_balance_mode = false > replicate_select = false > > Selects go only to master. Yes. > And those two should be the same: > load_balance_Mode = true > replicate_select = true > > load_balance_mode = false > replicate_select = true They should, but let's wait for Tatsuo's confirmation. > How does pgpool decide if a query is a select (load-balance possible) > or an insert/update (must be executed on all nodes). Specially what > happens in a transaction? Is a transaction always executed on all > servers, even if someone is just using selects in the transaction? pgpool-II won't do load balance when there are select and insert/update/delete statements in the same transaction. Instead, it will execute all queries against the master node and the insert/update/delete ones against the slave node only. > We rely on sequences to generate primary keys. If insert/update > queries are executed on multiple backends, they might be executed in > different orders, so generate different primary keys. > > How to avoid this? Locking the tables. > using insert_lock=true locks the table and then execute the insert. > No > Paralell execution, so no different execution order. What happens if > i > do a "select nextval(seq);" No locks. Might go out of sync? Yes, it might. > Any other way to avoid problems with sequences? Not using them. Try relying on business logic to generate ids. -- Jaume Sabater http://linuxsilo.net/ "Ubi sapientas ibi libertas" _______________________________________________ Pgpool-general mailing list [email protected] http://pgfoundry.org/mailman/listinfo/pgpool-general
