[Koha-devel] Adding support for PostgreSQL, no new MySQLisms, please

[Marc Balmer]

Am 24.03.12 15:07, schrieb Robin Sheat:
> Op 25-03-12 03:01, Marc Balmer schreef:
>> We adress this problem with the DBQ module, which exists to produce
>> database specific SQL code when there is no standard way to express sth
>> and when there is no way to get it through DBI.  See the example we
>> bundled with the path in bug 7365.
> 
> I'm not going to read the code because it's 3am, but does it rewrite the
> reports people enter or something? That seems dangerous unless done
> super-carefully.

No, it does not rewrite any reports.  If users enter SQL somewhere, I
assume they enter proper SQL for their DB server.  Which leads to a
small problem:  Reports that people share should be flagged as MySQL
only, PostgreSQL only, or portable.  Well, at least once Koha runs on
sth different than MySQL...

I am considering to write a set of compatability functions for
PostgreSQL that add the most used MySQL functions, but I don't know yet
how to mimick server crashes and data loss that can occur in MySQL :>

> 
> (Also, the DBQ stuff seems to be quite underdocumented. It doesn't even
> say what it is!)

Id'd say it becomes clear once look at the bug and code.  DBQ stands for
Data Base Query and ir produces database specific SQL.  It must only be
used where there is no other way to get the job done (i.e. don't use it
to produce DB specific code when there is a standard SQL way of doing so
or when there is corresponding functionality in DBI).

- mb