On 21.01.2025 20:33, Theodore Ts'o wrote:
On Tue, Jan 21, 2025 at 07:47:24PM +0100, Gerhard Wiesinger wrote:
We are talking in some scenarios about some factors of diskspace. E.g. in
my database scenario with PostgreSQL around 85% of disk space can be saved
(e.g. around factor 7).
Worse, using a transparent compression breaks the ACID properties of
the database. If you crash or have a power failure while rewriting
the 64k compression cluster, all or part of that 64k compression
cluster can be corrupted. And if your customers care about (their)
data integrity, the fact that you cheaped out on disk space might not
be something that would impress them terribly.
BTW: Why does it break the ACID properties?
Typically the transaction log will be (and have to be) flushed/synced to
disk (fsync). If that's ok everything is fine and all DB transactions
can be forwared if necessary. If that fails the last transaction is not
recorded.
I also don't see any compression related. That can also happen without
compression.
Any clarification?
Ciao,
Gerhard
