Working (basic) PgSQL->MySQL converted (was: Re:PostgreSQL to MySQL schema differences)

[Christopher Browne]

On 11/25/05, Andrew Hammond <ahammond-swQf4SbcV9C7WVzo/KQ3Mw at public.gmane.org> wrote:
> The next issue raised is typically performance. The analogy I
> typically offer here is MS IIS vs UNIX/Apache. IIS can serve static
> pages slightly faster than Apache. But who cares? Static content
> isn't very interesting anymore. Similarly, with databases, it is
> common to see benchmarks which fail to address critical issues such
> as concurrency, and query complexity. Worse, they are typically
> generic designs which fail to take advantage of any features which
> are not common to all the databases being examined. This is clearly
> leads to misleading results.

Yeah, that is not a bad analogy.

The thing I tend to find with web servers is that I almost never
actually want anywhere near the amount of functionality (and cost) of
Apache.  What I normally use is Boa, which is one of the ones
"attuned" to being dead cheap for handling static material.

And note that the issue that I normally have is that Apache forces you
to make so many configuration choices that THAT is what gets to be a
big pain.

> > If your PostgreSQL database sticks to mostly stock SQL calls the
> > converter should work. As it is I can use the converted to change
> > my stock 'postgres.schema' file to a 'mysql.schema' file that will
> > load into MySQL properly.
>
> Supporting multiple database platforms can make sense for
> applications which make only trivial use of the database. Beyond
> that, it becomes design for the lowest common denominator.

In effect, if you're using a database in "dead simple" ways, such as
using it to store a single table consisting of IDs and passwords (as
one might do authenticating with PAM and a DBMS), where typical
latency time makes small variations in time irrelevant, or in mapping
email aliases (as with Postfix), it will be pretty irrelevant what
database you choose to use.

> http://www.powerpostgresql.com/Downloads/database_depends_public.swf

There is a version as an OpenOffice.org presentation; it is well worth reading.

I used to work with SAP R/3 systems.  They *typically* are run atop
Oracle, though IMS, DB2, Adabas, Adabas-D, Microsoft SQL-Server, and
Informix have also been supported (the Mainframe-only ones for R/2). 
Unfortunately, performance is something that does tend to suffer.

R/3 has fairly spectacular hardware requirements.  It is common to
spend millions of dollars on the servers in order to support
surprisingly small numbers of concurrent users...

Historically, SAP has had pretty good reason to try to be somewhat
DBMS-agnostic; their choices would have been twofold:
 1.  Become dependent on the good graces of sharks like Larry Ellison
 2.  Build their own DBMS which would be a barrier to sales

Unfortunately, the alternative they chose, being DB-agnostic, means
that you have to buy a whopping lot of hardware since the application
needs to be "attuned" to what amounts to the *worst* that all have to
offer.
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