[wp-hackers] GSoC Proposal: Multiple RDBMS support

Jacob Santos wordpress at santosj.name
Mon Mar 31 13:04:54 GMT 2008

Well, okay, sorry, I meant some of that for Alex, but thanks for replying

Your Factory solution sounds a lot like the one I thought about for 
replacing the hackish kind of method. I do think it would be kind of 
better to extend the WPDB class to get some of the nice methods inside 
of it.

It also sounds like your be reinventing the wheel. However, I do suggest 
you look at the Zend Framework and the DB component to see how they do 
it. You might not learn anything you don't already know, but it would be 
interesting, since they are basically reinventing the wheel also.

I do like the fluid chaining. I use it in a current project with decent 
enough results.

However, I like Alex said, this probably will not be accepted, because 
it will have to support PHP4.3 which is a requirement of WordPress at 
this moment and in order to do a Google Summer of Code project for 
WordPress, it will have to support PHP4.3. Also, it is not probable that 
your project will be included into the core.

If you start coding it now, then by the time PHP5 is the minimum 
requirement, then you'll already have your project finished or mostly 

Best regards, as a programmer, it does sound extremely fascinating, 
because it is not a project I would do myself (probably use an existing 
framework myself).

Olexandr Melnyk wrote:
> Hey,
> On 3/31/08, Chris Poteet <cpoteet at siolon.com> wrote:
>> Yes, even though this has been talked about before but for good
>> reason.  Like my new plugin which uses SimpleXML which is much easier
>> than the PHP4 way of parsing XML.  I was in Barnes and Noble and saw a
>> book for PHP6!  Now, we're really lagging behind.
> I am a proponent of PHP5 as well. WIth the wide use of WordPress, if it
> becomes PHP5-only, pretty much all hosts will be supporting it soon :)
> But let's get back to the topic, this discussion is about something
> a little bit different here.
> On 3/31/08, Jacob Santos <wordpress at santosj.name> wrote:
>> Do you propose an adapter, factory, or registry pattern for
>> accomplishing this? The way your code looks, it looks like what can
>> already be done now with replacing the WPDB class with one of your own.
>> You would have to do replacements of the SQL.
> We could use a factory for instantiating an obect of
> proper database-specific WPDB ancestor class. Registry could work for
> storing "wpdb" object, but changing to
> this approach from storing wpdb object in a global variable, like it
> is done now, would break (almost)
> all existing plugins, and that is not a point here.
> Also, it appears you are talking about Database *Access* Abstraction
>> Layer and SQL Abstraction Layer. The Access Abstraction is already
>> accomplished and while pretty damn crappy (you have to support PHP4 you
>> know), I do think PDO would kick WPDB ass and probably be a lot faster
>> too.
> I was going to suggest PDO for database abstraction too, but realised
> that it won't work for the same reason.
> However, PDO would not solve your SQL abstraction and your Access
>> abstraction is already solved, so there would be no need to do this.
>> Unless you wanted to remove the global variable usage and allow for one
>> of the above patterns to have the database replacement in a plugin
>> instead of in the wp-content folder with a specific name in order to be
>> included and replace the current WPDB class.
>> SQL is not that difficult to learn, therefore it would logical assume
>> that if one knows one SQL language, one can also learn another. Given
>> that, I think handling RAW SQL instead of arrays would work better.
>> However you go about doing so would be interesting. However, I don't
>> suggest your current mockup, because I'll hate you for creating
>> something so overly complex.
> There are a number of approaches for this, one is to use a "clauses  chain"
> like this: $wpdb->select('user_login')->from('users')->where('ID = 1');
> Despite this could be a "new" way of writing SQL, we'd still have to support
> the old interface.
> Well, technically it would range from extremely easy but redundant to
>> extremely difficult, depending on which method you choose. The plugin
>> would just say, this plugin is MySQL only like in other systems I've
>> seen. If the user wants another database support, the user can add it
>> themselves.
>> It is a fact, that not coding in strict SQL 92 format and manually
>> targetting one RDBMS, allows for better support, quicker development,
>> and better optimization.
> Agreed on both, but as I said, with the MySQL
> feature set used by WordPress, it shouldn't make a huge difference
> whether one or multiple databases should be targeted (as
> long as all of them understand an SQL dialect).
> It is not a fact that it won't meet most target audiences, want about
>> companies who already use Oracle and don't want to have to buy a MySQL
>> server just to run WordPress? Force them to write their own WPDB class
>> and replace the SQL by regular expressions?
> Replacing SQL by regex would be a quick and dirty solution. It could
> also make a some of plugins work
> on number databases, but it wouldn't be a good idea in the long run.
> It is not a fact that it will require plugin authors to support RDBMS,
>> unless it was made a requirement. It would be completely up to the
>> plugin developer. If that plugin developer only wanted to support SQLite
>> or Oracle, than that would be their priority and audience. If another
>> person wanted to add MySQL or another, then it would be added.
> Agreed, if developer finds particular database functionality more useful
> for his/her plugin than database abstraction, s/he can use it.
> Another fact is that it is not very hard depending on how you implement
>> it, the current implementations only make it seem that way because they
>> abstract everything and hold your hand. That implementation would be
>> extremely difficult and not worth the time it would take. An
>> implementation that is just an array that WordPress looks for the key
>> for the database and pulls that SQL statement out, would be easy,
>> however hackish.
> What I would suggest to use for now is to split WPDB into two parts. One
> would provide database abstraction (query, fetch row, get error etc) and
> will be implemented for every supported database.
> Another will have the same interface as current WPDB (so it won't break any
> plugins) and will be based on calls to the abstraction layer (so it will
> have to be implemented just once), instead of
> mysql_* functions, as it is done now.
> We'd also have to expand WPDB class with a couple of methods,
> used for the SQL statements/clauses that have varying syntax among different
> databases. As far as I'm aware, WordPress makes use of two such
> features: one is fulltext search and another is limit
> clause.FOr the former we could have a method fulltext_matches(), which would
> return an appropriate WHERE condition.
> For the latter, we could use something like:
> $result = $wpdb->query(limit('SELECT user_login FROM ' . $wpdb->users . '
> ORDER BY user_login', 0, 10));
> The implementation for MySQL, PostgreSQL and SQLite would be somewhat
> straightforward, and would require some more work for SQL Server and Oracle.
> Thanks for the replies


Jacob Santos

http://www.santosj.name - blog
http://funcdoc.wordpress.com - WordPress Documentation Blog/Guide Licensed under GPLv2

Also known as darkdragon and santosj on WP trac.

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