John R Pierce wrote:
chris wood wrote:
At a detailed level (which is NOT the direction I want this thread to
go) I do not agree with your statement that my proposal has no “hope
of ACID compliance or transactional integrity”. When the “slices” are
stored back to the cloud, this is the equivalent of a commit and the
integrity thereof is as good as what ever the underlying technology
is. Is the concurrency as good as native Postgres? Of course not. Is
the commit/rollback flexibility as good as native Postgres? Again no.
But what’s the alternative? Watch cloud computing take off leaving
Postgres with the reputation of “great database software in
yesterday’s era of monolithic servers”?
even something as simple as a SERIAL sequence would be a nightmare in
a distributed cloud environment without a complex centralized
arbitrer. the same goes for most any other sort of update/query that
depends on consistency of data.
How do you reconcile a bank account when the money has been
simultaneously withdrawn from several ATMs at different locations at
the same time? "Please, sir, give us our money back?" ? I don't think
the banks would be happy with that implementation.
If the data is partitioned across the cloud ('one version of the
truth'), things like JOINs are very very difficult to implement
efficiently. take away JOINs and you might as well be doing simple
ISAM like we did back in the 70s before Codd and his Relational
Database concepts upon which SQL is based.
no, IMHO, the cloud people are better off inventing their own data
models and their own proprietary query languages suited to the
architecture. maybe SQL and its concepts of 'one version of the truth'
and 'data integrity' are quaint relics of another age, so be it.
Objecting to an idea because it is difficult to implement is not
necessarily a clincher - there are projects trying to adapt Postgres to
more cloud-like capabilities (e.g Greenplum, Netezza) - neither of these
are open source however. There is also Pgcluster, however I'm not sure
that counts as cloud-like in its architecture...
regards
Mark
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