Re: Limitations of PostgreSQL

On Wed, 2005-10-12 at 23:11, Chris Travers wrote:
> Scott Marlowe wrote:

> >Thought I'd comment on this.
> >
> >According to the author of the innodb engine, innodb uses MVCC.
> >OTOH, I consider innodb to be broken in production, due to issues with
> >constant growth and no way to reclaim the lost space.
> >
> >
> Any sources on that? I would love to have info on that.

Just do a google search for innodb and mvcc. Lots of soruces, not sure
how good any one might be.

> >This means that vacuuming, a minor annoyance in PostgreSQL, is a major
> >issue for 24/7 mysql databases running on innodb, where they must be
> >shut down and restarted to clear up the unused space in the innodb
> >tablespace.
> >
> >
> >
> >
> No kidding. Would like more info.

Setup a MySQL database with 5.0.13 and insert and delete a lot in an
mvcc table. The innodb tablespace just grows and grows.

> >>Multimaster async replication w/updates is a pain at the moment and
> >>mostly a set of kludges.
> >>
> >>
> >
> >There really are too many use cases for there to be a "simple"
> >resolution to the problems presented by multi-master replication. It's
> >a complex problem that creates more complex problems as you attempt to
> >solve it.
> >
> >
> I have come up with some ways of doing this but they are difficult. And
> the question is always "How good is good enough"

Right, and the real issue is that what might be a good compromise
between performance and data security in one situation might be an awful
choice in another. So, multi-master replication isn't likely to become
a plug in module for postgresql any time soon.

> >>Does not have full XA support at the moment (does have TPC).
> >>
> >>
> >
> >I'd point out here that MySQL's XA support is quite primitive, and only
> >useful for a fairly smaller number of cases.
> >
> >
> Again, I was comparing with DB2 and Oracle. One should consider all new
> features of MySQL to be both overmarketed and primitive for some time.

True. PostgreSQL IS working on XA support (specifically the jdbc list
is.)