Guten Tag Daniel Verite, am Montag, 8. Juni 2020 um 12:07 schrieben Sie: > But a SQL session on the server takes its statements from a FIFO queue > and processes them serially, so there's no intra-session concurrency. > In fact multi-threaded SQL clients *must* make sure that they don't > send concurrent queries to the same connection.[...] I was looking at JDBC-docs and those explicitly allow sharing one connection by multiple threads, while at the same time not explicitly forbidding concurrent access. https://docs.oracle.com/javadb/10.8.3.0/devguide/cdevconcepts23499.html https://docs.oracle.com/javadb/10.8.3.0/devguide/cdevconcepts89498.html Therefore I had assumed that concurrent access is available as long as one follows the recommened practices, which is what I do. Though, that concurrent access seems to not be available because of additional synchronization in the JDBC-driver of Postgres. https://stackoverflow.com/a/52798543/2055163 https://github.com/pgjdbc/pgjdbc/blob/ecbc48ff6ad293a2555465d4f7fb6a33a403af26/pgjdbc/src/main/java/org/postgresql/core/v3/QueryExecutorImpl.java#L276 Is that the case with all JDBC-drivers most likely or simply some implementation detail of some and others might allow truly concurrent access within one session? Nevertheless, I think I can at least partly answer some of my questions now. So thanks for forcing digging deeper into this than I obviously did before. :-) Mit freundlichen Grüßen, Thorsten Schöning -- Thorsten Schöning E-Mail: Thorsten.Schoening@xxxxxxxxxx AM-SoFT IT-Systeme http://www.AM-SoFT.de/ Telefon...........05151- 9468- 55 Fax...............05151- 9468- 88 Mobil..............0178-8 9468- 04 AM-SoFT GmbH IT-Systeme, Brandenburger Str. 7c, 31789 Hameln AG Hannover HRB 207 694 - Geschäftsführer: Andreas Muchow
