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Date: Thu, 6 Sep 2012 01:31:13 +0200
Cc: PHP Internals List <internals@lists.php.net>
To: Daniel Convissor <danielc@analysisandsolutions.com>
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Subject: Re: [PHP-DEV] mysqli_fetch_field() mysqlnd & libmysql differences
From: johannes.schlueter@oracle.com (=?utf-8?Q?Johannes_Schl=C3=BCter?=)

Hi,

On Sep 6, 2012, at 1:24, Daniel Convissor <danielc@analysisandsolutions.com>=
 wrote:

> Hi Johannes:
>=20
> On Thu, Jan 19, 2012 at 01:50:47PM +0100, Johannes Schl=C3=BCter wrote:
>>=20
>>        unsigned long length
>>=20
>>        The width of the field. This corresponds to the display length,
>>        in bytes.
>>=20
>>        The server determines the length value before it generates the
>>        result set, so this is the minimum length required for a data
>>        type capable of holding the largest possible value from the
>>        result column, without knowing in advance the actual values that
>>        will be produced by the query for the result set.
>>=20
>>        http://dev.mysql.com/doc/refman/5.5/en/c-api-data-structures.html
>=20
> Pardon me for looping back around to this old discussion.  I had a
> moment to look at this in PEAR::DB the other day.  A new perspective
> came to mind...
>=20
> It seems the field length in the C API is there to aid C programmers
> with memory allocation.
>=20
> The field length in PHP is there for PHP programmers to reverse engineer
> database structures.
>=20
> These are different purposes and the output should reflect such.
>=20
> For example, the userland PHP field length could lead to someone dumping
> a structure that has a VARCHAR(10).  The exported metadata would say
> VARCHAR(30).  Then it gets imported and dumped again, and now we're up
> to VARCHAR(90).  Not fun.

This is all correct - but there isn't much we can do. The server provides th=
is data. Trying to "fix" it on the client side will likely become a mess. If=
 we create a mess I prefer doing it in user land (db2, mdb, doctrine, propel=
, ...) where "everybody" can debug/fix it.

Johannes

> Thanks for your reconsideration,
> --Dan
>=20
> --=20
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