Edson, > Em 17/11/2013 19:26, Stefan Keller escreveu: > > Hi Edson > > > > As Rob wrote: Having a feature like an in-memory table like SQLite > > has > > [1] would make application cahces obsoleteand interesting to > > discuss > > (but that was'nt exactly what I asked above). > > Hi, Stephan, > > I don't think any feature you add to database server would bring > obsolescence to app server caches: app server caches have just no lag > at > all: > > 1) Don't need network connection to database server > 2) Don't need to materialize results (for instance, I have in mind a > Java or .Net app server running hundred thousands of objects in > memory). > > IMHO, no matter how much you improve database, app server caches > provides additional level of speed that cannot be achieved by > database. > > That said, I still can see huge improvements in database server. > Having strong in memory operation would bring substantial > improvements. > For instance, if you have in-memory database (tables, indexes, etc) > for > all sort of queries, and just **commit** to disks, then you will have > unprecedent performance. > I would get benefit from this architecture, since typical customer > database has < 64Gb on size (after 2 or 3 years of data recording). > So, > a database server with 64Gb of memory would keep everything in > memory, > and just commit data to disc. > > In this case, commited data would be instantly available to queries > (because they are all in memory) while log (changes) is recorded in a > fast disk (a SSD, perhaps) and then those changes are made persistent > data, written async into slow massive disks (SCSI or SAS). > > This would allow also a hybrid operation (too keep as much data pages > as > possible in memory, with a target of 50% or more in memory). > > When database server is started, it would have lazy load (data is > loaded > and kept in memory as it is used) or eager load (for slower startup > but > faster execution). not sure I fully understand your point. Isn't this the typical mode-of-operation plus added cache warming? Anyways, just wanted to point you to [1] which gives a good overview of cache warming techniques. Regards, Andreas [1] http://raghavt.blogspot.fr/2012/04/caching-in-postgresql.html -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
