Thank you very much, Laurenz Albe.
On Mon, Jun 10, 2013 at 9:21 AM, Albe Laurenz <laurenz.a...@wien.gv.at>wrote: > Gustavo Amarilla Santacruz wrote: > > In the PostgreSQL documentation I found "currval: Return the value most > recently obtained by nextval > > for this sequence in the current session ...." > > > > In other documentations (pgpool, for example), I found "Connection > Pooling > > pgpool-II saves connections to the PostgreSQL servers, and reuse them > whenever a new connection with > > the same properties (i.e. username, database, protocol version) comes > in. It reduces connection > > overhead, and improves system's overall throughput" > > > > Then, I have the following question: PostgreSQL differentiates between > sessions created for the same > > user? > > > > Background > > ========== > > - I, traditionalmente, have several user in a web application (user > table, for example); but I use > > only one postgresql-db-user to get connetions to database > > > > - If a CREATE (CRUD) operation uses a head-detail couple of tables, then > in a transaction: data in > > HEAD table is inserted; next, the value for the primary key is achieved > from currval function; next > > references to head table is inserted in detail table. > > "currval" will return a different value or an error message if > the query happens to use a different session than the one that > you used for "nextval". > > The best way to solve this is the INSERT ... RETURNING statement, > like in INSERT INTO t VALUES (...) RETURNING id, which will > return new value of the automatically generated column. > > Yours, > Laurenz Albe > -- ------------------------ Gustavo Amarilla
