re: Gaining access to data outside the current database
>Message-Id: <199203181310.AA21293@tbird.cc.bellcore.com> >From: uunet!hector.cc.bellcore.com!warren (saccente,warren j) >Date: 18 Mar 1992 8:05 EST >Subject: re: Gaining access to data outside the current database >X-Informix-List-Id: <list.963> > >With Informix Online you can select from a remote db by refering to the >table as DBNAME:TABNAME, but I believe that you cannot do any updating >in this manner. > >Warren J. Saccente >Bellcore Two additions to what Warren says: a. Updatability depends on the version of OnLine, as in the table below. b. You can also use synonyms to represent remote tables. A synonym looks like a local table name but can resolve into a remote table name. eg: CREATE SYNONYM Owner1.Table1 FOR Database2@Machine2:Owner2.Table2 Can a single transaction access a non-current database? +==========+=========================+============================+ |OnLine | Same OnLine System | Different OnLine Systems*| |Version | Read Write | Read Write | +==========+============+============+==========+=================+ |4.00 | Yes | No | Yes | No | +----------+------------+------------+----------+-----------------+ |4.10 | Yes | Yes | Yes | No | +----------+------------+------------+----------+-----------------+ |5.00 | Yes | Yes | Yes | Yes | +==========+============+============+==========+=================+ * Requires Informix-STAR. Version 4.00 provides read-only access to other databases. If the other database is part of the same OnLine system, Informix-STAR is not required. Version 4.10 provides read-write access to other databases which are located in the same OnLine system without requiring Informix-STAR. It provides read-only access to databases in other OnLine systems. Version 5.00 provides read-write access to other databases. If the other database is not in the same OnLine system as the current (or home) database, then the system must use Informix-STAR. Version 5.00 automatically provides 2-phase commmit if a single transaction updates more than one database in more than one OnLine system. Yours sincerely, Jonathan Leffler (johnl@obelix.informix.com)
You can also update two databases transactionally through the use of multiple application servers (AS) in a transaction processing (TP) system (such as Encina). Each AS updates a database, and the TP system coordinates the 2PC among them, even in the absence of Informix-STAR. -Mark