2011/5/4 durumdara <durumdara@xxxxxxxxx>: > Hi! > > We will porting an application to PGSQL from some table based app (BDE > like). > > The older application used a special technic of the driver: if a record > edited, some exclusive (over transaction), "forever living" lock put on it. > On exit, cancel, or post this lock removed. > > We used this to lock the main resource from concurrent edits. > > For example: > A product (a Car) have many properties and sublists (details), like color, > transport date, elements (what we need to build into car: wheel, etc), bill > informations, subtransport times, etc. > Because ALL of them is the product, we must protect it with "Edit lock" on > open. > The subinformations are easily editable, and postable (there is autocommit). > > Now I search for some technics in PGSQL. > As I read, the locks are transaction depended, because they are vanishes on > rollback/commit. > > But we want to save the subelements on editing (one by one), not on saving > the main. > This meaning that we break the transaction with commit - ergo the lock > vanish. > > For example: > Car Edit: > - Lock This car > - Edit color > - Open product elements tab > - Add two new elements > - Save them (ApplyUpdates, Commit) > - Add a bill date > - Save it (Apply, Commit) > - Post car record (Apply, Commit) > - Release resource > - Close Form > > I read the help, but I saw only transaction-dependent locks. > > Zeos or PGDAC is not like IBX/IBO (Firebird), so they don't have Transaction > Component, I can use only one transaction by connection. > > How can I do a lock mechanism that: > - Session based > - No limit on how many I used > - Linked to a Row, or a Resource Name > - I can test to is it exists or not > > Like Mutex in Windows, but in PGSQL... advisory locks http://www.postgresql.org/docs/current/interactive/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS (aside: borland delphi is increasingly obsolete in the scheme of things, but zeos is one of the best postgres drivers ever written!) merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
