Laurent Birtz wrote: > loop > BEGIN; > SELECT hits FROM webpages WHERE url = ...; > -- client internally computes $newval = $hits + 1 > UPDATE webpages SET hits = $newval WHERE url = ..; > if (no error) > break out of loop; > else > ROLLBACK; > end loop > COMMIT; I think you should be able to shave some milliseconds off that loop by using SAVEPOINTs instead of a full-blown transaction for each tuple. Something like BEGIN outer loop inner loop SAVEPOINT foo; SELECT hits ... UPDATE webpages SET hits = ... if (no error) break inner loop else ROLLBACK TO foo end inner loop end outer loop COMMIT; > However, I am having problem implementing this scheme in C with libpq. > Transactions can be aborted because a deadlock occurred or another > transaction already made some changes to the database. > > My question is how exactly do I detect that this occurred? IIRC you can apply PQresultStatus to the PGresult returned by the UPDATE. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc. ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your message can get through to the mailing list cleanly
