Martijn Tonies wrote:
> Given that the OP did not state that there were any issues with an
> existing website, logical requirements come first. Period. No discussion ;)
Logical requirements may come first, but may be overruled later by
requirements caused by performance issues or system limitations.
If your logic designed a large type of primary key, you may run into
problems with InnoDB tables. The PK is stored with the data and other
indexes refer to the PK (and not directly to the data as is the case
with MyISAM). So a large PK will increase the table size (data +
indexes) and may thus lead to performance issues when the database does
not fit in memory anymore, or when the buffers,etc. hit the memory
limits on your system.
A very complex model may lead to queries with more than 31 JOINs, which
is not possible with MySQL without modifying the source and recompiling
it (and even then the limit seems to be 63).
> In any case, if this is a read/write application, I would still say that
> logical
> requirements should go first. If this is a read only application, do
> whatever
> you want.
Logic may come first in the time line, but may be overruled by other
requirements. Finding people who celebrate their birthday today (or this
week) may become a very slow task if you only use a logical data field.
Denormalisation by using extra fields for particular tasks is a
completely logical solution in this case.
> If this is the customers own server and everything is logical correct but
> there
> are "some" performance problems, I'd say: throw more hardware at it.
> Obviously, this makes sense --after-- tweaks to the database engine caching
> etc etc... Hardware is cheap(ish). If you can control it, do so.
"Throwing" hardware at it is not always a good solution. You know better
than that. The customer better not find out that the application could
very well run on the original server with a few "tweaks" as you call
them, and that he appears to have lost a lot of money for new hardware
and all the time needed to get the new server running in the
configuration that you suggested...
Regards, Jigal.
