that's more a place for unittesting the app itself than having web2py to 
check for it for every db (and every version of engine) at all times.
It's true that DAL absracts away the 90% of incompatibilities, but still 
you *need* to evaluate your choices when it comes to a production app, 
being aware of all pros and cons.

On Wednesday, April 3, 2013 8:40:16 PM UTC+2, Chris wrote:
>
> It would probably be difficult to keep DAL up to date with DBMS releases 
> -- would hate to have to rev some part of web2py every time even one of the 
> supported DBMSs has a version change.  And even then, version alone may not 
> answer the question, since max field lengths can be affected by database 
> configuration options as well.
>
> A better solution would be for DAL to probe the actual DBMS capabilities 
> -- if there is a question about an issue like a max string length, allow 
> DAL to control one table (dbms_capabilities?) that can be used to test 
> actual limits.  E.g. if a DB model file specifies a string field of length 
> 8000 and that is above the previously-tested limit, drop and create 
> dbms_capabilities with a string(8000) field, write 8000 characters to it, 
> read it back, and see if the result matches the input.  This would be a 
> very thorough way to find the limits of any database exactly as configured.
>
> Not sure if this would be needed for other data types too (decimal 
> precision or ??) but could be generalized.
>
> The original problem of silently accepting a database definition that the 
> DBMS can't produce is really concerning.
>
>
>
>
> On Friday, September 14, 2012 9:39:14 AM UTC-4, Chris wrote:
>>
>> ... whatever the max length is for the particular DBMS / version, if the 
>> Field() call specifies a length longer than the max, return the same error 
>> as for other invalid field lengths (like -1).
>>
>>
>>

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