Hi Yeb Thanks for the pointers.
Of course disk access is not obsolete: As I said, I suppose changes are streamed to disk. When I mentioned "no disk access" I meant the indices of RDBMS which designed to handle disk access - which seems to me different in in-memory dabases. The paper referred by you is coming from SAP's chief scientist and it confirms actually my claim, that there's no need for a primary index since the primary attribute (i.e. all attributes) is already kept sorted in-memory. It also mentions an insert-only technique: "This approach has been adopted before in POSTGRES [21] in 1987 and was called "time-travel". I would be interested what "time-travel" is and if this is still used by Postgres. Finally the paper is mostly about column stores - nothing about persistence. In mentions Disaster recovery" in the last section about future work, though. -S. 2014-04-01 21:57 GMT+02:00 Yeb Havinga <yebhavi...@gmail.com>: > On 2014-04-01 04:20, Jeff Janes wrote: > > On Sunday, March 30, 2014, Stefan Keller <sfkel...@gmail.com> wrote: > >> Hi Jeff >> >> 2013/11/20 Jeff Janes <jeff.ja...@gmail.com> >> >>> >>> I don't know what you mean about enhancements in the buffer pool. For >>> an in-memory database, there shouldn't be a buffer pool in the first place, >>> as it is *all* in memory. >>> >> >> You are right: In-memory DBs are making buffer-pooling obsolete - >> except for making data persistent (see below). >> > > > I would be very reluctant to use any database engine which considered > disk access obsolete. > > > The disk is not obsolete but something called 'anti-caching' is used: > http://www.vldb.org/pvldb/vol6/p1942-debrabant.pdf > > > > > Are there any show cases out there? >> > > What did the HANA users have to say? Seems like they would be in the > best position to provide the test cases. > > > This paper provides some insights into the research behind HANA > http://www.sigmod09.org/images/sigmod1ktp-plattner.pdf > > regards > Yeb > >