On 2014-11-02 12:11:49 +0000, Mikko Tiihonen wrote: > > From: Andres Freund <and...@2ndquadrant.com> > > On 2014-11-01 14:04:05 +0000, Mikko Tiihonen wrote: > > > I created a proof of concecpt patch for postgresql JDBC driver that > > > allows the caller to do pipelining of requests within a > > > transaction. The pipelining here means same as for HTTP: the client > > > can send the next execution already before waiting for the response of > > > the previous request to be fully processed. > > > > Slightly confused here. To my knowledge the jdbc driver already employs > > some pipelining? There's some conditions where it's disabled (IIRC > > RETURNING for DML is one of them), but otherwise it's available. > > > > I'm very far from a pgjdbc expert, but that's what I gathered from the > > code when investigating issues a while back and from my colleague Craig. > > Most DB interfaces make the server operations look synchronous.
You IIRC can use jdbc's batch interface. > I should have searched earlier a better reference to libpg. I am planning on > adding support for something similar to > http://www.postgresql.org/docs/9.3/static/libpq-async.html > More specifically operations like: > int PQsendQuery(PGconn *conn, const char *command); > PGresult *PQgetResult(PGconn *conn); That doesn't really support pipelining though - you can still only send one query. It's nonblocking, but that's a different thing. > In libpg terms: Is it safe to do multiple PQsendQuery operations > before invoking PQgetResult as many times? The network protocol allows for pipelining, yes. But libpq unfortunately doesn't. You should read the protocol definition. > It should be, if the server startd to process (read in) the next query > only after it has sent the previous response out. There's complexities around error handling and such making it slightly more complex. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
