Christopher Jones wrote:
Lester Caine wrote:
I keep being told that the PDO drivers can be extended to include all
of the things already available in the native driver, but the second
you do that they become incompatible, so in addition to the PDO driver
you need to also run the native driver simply to provide the areas NOT
covered by PDO. We need a generic framework that addresses the real
problems not one that creates an artificial lowest common denominator
strangle hold :( PDO could evolve into that, but not with it's current
restrictions.
Can you list the current restrictions as you see them?
Actually the very first one has been addressed and has nothing to do with PDO.
Up until recently is was essential to provide backwards compatibility with
PHP4 and all of the projects I currently work with WOULD still install on
PHP4. Although *I* never used it in production, the continued support meant
that there was a large base that insisted on retaining it. So ADOdb's
continued underlying support for PHP4 is useful and until there are a higher
percentage of PHP5 users than PHP4 - PDO takes second place as it is not
available on a large number of hosts?
The next problem builds on the above one. From the PDO manual "PDO does not
provide a database abstraction; it doesn't rewrite SQL or emulate missing
features. You should use a full-blown abstraction layer if you need that
facility." ADOdb will run PDO drivers quite happily, but on current
information the performance of the PDO drivers is slower than using the same
native driver. So given a choice the native one is preferable and currently
essential for PHP4 support.
NEITHER of the above are restricted to Firebird and apply equally to all
databases, but they are the main reason to date that no one has had the
inclination to fix the pdo_firebird driver as it's deployment potential is
currently limited.
The internals of PDO restrict things to using SQL access to the database.
While it will probably be said that the database should ONLY provide SQL
access to everything, Firebird has a services interface which is used for such
things as backup, user management, and the event handler. How should all those
be handled if they are moved to the PDO driver?
PDO provides a basic transaction control that hides the transaction modes. It
can't handle retaining the context of the transaction following a commit or
roll back, or selection a more appropriate transaction mode? CONCURRENCY for
reports at a fixed time point over COMMITTED to handle changes made in other
transactions. How does one switch between a 'wait' and 'nowait' transaction?
The one that prompted this discussion. How do you return a simple handle to a
BLOB object so that you DON'T have to download the whole blob. It can be
useful to hold the blob id so that you only access a sub set of the data from
the blob object. This seems to be missing in PDO?
HAVING to maintain PHP4 support has meant that I have not gone into PDO with a
fine tooth comb, and most of my understanding of the problems of PDO is based
on what has been said elsewhere, but at present I can't see how some of these
fundamental facilities provided by the php_interbase driver would be mirrored
in PDO. I stand to be corrected, and perhaps when PHP4 has died THEN the
supposed advantage of PDO may be a more attractive development path? But at
present there is simply no incentive to move over :(
--
Lester Caine - G8HFL
-----------------------------
Contact - http://home.lsces.co.uk/lsces/wiki/?page=contact
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Firebird - http://www.firebirdsql.org/index.php
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