[EMAIL PROTECTED] ("Jeff Larsen") writes: >> Alvaro Herrera wrote: >> > Glyn Astill wrote: >> >> Thanks everyone for your replies. EnterpriseDB looks like the way to >> >> go if we want good replication. >> > >> > Sorry, this makes no sense to me -- EnterpriseDB has no replication >> > solution that I know of. >> >> Yeah, there is: >> >> http://www.enterprisedb.com/products/enterprisedb_replication.do > > Yes, but I'd like something better than "near real time" as the above > page describes. Or maybe someone could clarify that.... Besides, > EnterpriseDB does not save me enough money. In my current commercial > DB, if a transaction is committed on the master, it is guaranteed to > be committed to the secondary. In our business, losing one customer > order could lose us the customer for good.
I believe that what they are using is a version of Slony-I, which certainly falls into the "near real time" replication category. Historically, when people think they require "something better than near-real-time," they frequently find that the "something better" turns out to be too expensive to live with. "Near real time" usually refers to the notion of asynchronous replication, where it is a little bit nondeterministic how far behind a replica may be. (Which is definitely the case for Slony-I.) Unfortunately, the only way to make things deterministic (or to get from "near real time" to "*GUARANTEED* real time") is to jump to synchronous replication, which is not much different from 2PC (Two Phase Commit), and which is certain to be prohibitively expensive across a WAN. At this point, I tend to get visions of Tom Cruise telling Jack Nicholson, "I want real time replication!", and getting the response: "You can't HANDLE real time replication!" -- (format nil "[EMAIL PROTECTED]" "cbbrowne" "linuxfinances.info") http://cbbrowne.com/info/slony.html "Any sufficiently complicated C or Fortran program contains an ad hoc informally-specified bug-ridden slow implementation of half of Common Lisp." -- Philip Greenspun ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org/