Re: Extract SQL-Engine basics from DBD::File

Jens Rehsack wrote:
> during refactoring of DBD::File and new wishes (e.g. SQL_IDENTIFIER_CASE
> from Martin Evans, getinfo() support, ...) and my own try of a pure-perl
> DBD for system tables (DBD::Sys) I see many common code.
> 
> I would like to extract the common code into a base class DBD - maybe
> named DBD::SQLPerl (placed SQL in from for private methods and attributes
> naming - the should have the prefix "sql_").

I had already been thinking of this need for awhile, but in that context it 
would have been a utility module, say with "common" in its name or something.

Unless there is already a precedent otherwise, I recommend leaving the DBD::* 
namespace for actual DBI drivers, and utilities go in some other namespace, 
though perhaps DBD::Util::* or something.

The choice may also be affected by whether the new module is meant to be 
subclassed by a DBI module or just "used" ... the latter makes more sense if it 
would be used by multiple component classes like the driver and statement 
handles, unless the utility has one for each of those, but I wouldn't make it a 
subclassing situation.

YMMV.

In any event, I intend to personally be doing akin to what you propose but more 
comprehensively, sometime around the August-September 2010 timeframe.  For about 
that time I would be making the reference implementation of my Muldis D 
language, which is a self-contained Perl relational DBMS with nearly all the 
features you'd see in a regular SQL DBMS, including multi-column joins, 
subqueries, unions, recursion, nested transactions, etc.

This would be componentized such that most of it could be reused directly as 
utilities to do what you want, such as by adding a SQL parser on the front and 
changing the storage end to talk to the system metadata or Google or CSV files 
or whatever.

Don't let that stop you from doing what you're doing though, which looks like 
more of a refactor, but I do intend to take it to the next level before long.

-- Darren Duncan

P.S.  See also Genezzo.