Re: RFI: Database URIs

Am 25.11.2013 um 20:42 schrieb David E. Wheeler <[email protected]>:

> On Nov 25, 2013, at 11:08 AM, Jens Rehsack <[email protected]> wrote:
> 
>> Let’s go - shoot:
>> 
>>   # specify most possible flags via driver flags
>>   $dbh = DBI->connect ("dbi:CSV:", undef, undef, {
>>       f_schema         => undef,
>>       f_dir            => "data",
>>       f_dir_search     => [],
>>       f_ext            => ".csv/r",
>>       f_lock           => 2,
>>       f_encoding       => "utf8",
>> 
>>       csv_eol          => "\r\n",
>>       csv_sep_char     => ",",
>>       csv_quote_char   => '"',
>>       csv_escape_char  => '"',
>>       csv_class        => "Text::CSV_XS",
>>       csv_null         => 1,
>>       csv_tables       => {
>>           info => { f_file => "info.csv" }
>>           },
>> 
>>       RaiseError       => 1,
>>       PrintError       => 1,
>>       FetchHashKeyName => "NAME_lc",
>>       }) or die $DBI::errstr;
>> 
>> And keep in mind, csv_tables can be more complex and there’re other
>> attributes like it eg. in DBD::AnyData.
> 
> Well, how you would want to handle params would be up to you. No, they are not great for hashes, but do-able.
> 
>    db:csv?f_dir=data&f_dir_search=foo&f_dir_search=bar&f_ext=.csv/r&f_lock=2&f_encoding=utf8&csv_eol=%0D%0A&csv_sep_char=,&csv_quote_char=%22&csv_escape_char=%22&csv+class=Text::CSV_XS&csv_null=1&RaiseError=1&PrintError=1&FetchHashKeyName=NAME_lc&csv_tables=%7B%22info%22%3A%20%7B%22f_file%22%3A%22info_csv%22%7D%7D

Happy hacking, when you want type that on command line. DBD::CSV (and other
Pure-Perl drivers) is designed for flexibility and quick setup, not for
expensive configuration and long-term running.

> So yeah, one would need to do some sort of parsting of nested data (JSON in the csv_tables example here), though arrays work okay (e.g., f_dir_search).
> 
> OTOH, can you specify all this stuff in a DSN parseable by parse_dsn(), either?

You can’t - this is a clear point in DBI::DBD::SqlEngine at the moment.

> But my point is not to replace the connect() API, but to create a standard of sorts for representing connection info in a URL, to make it easier to specify how to connect to things on the command-line. Yeah, if you want to do everything, it will require more work, but that would be up to the code that handles each driver, which is to say the URI subclass for a particular DBMS.

All I say to you: if you want DBI supporting that - keep in mind the
whole requirements. If you just want to do another DBI extension, with
limited coverage and usage - feel free.

> But this discussion orthogonal to my original questions, which were:
> 
> * Should I use a hierarchical scheme like JDBC? I’m leaning heavily toward this now, just need a decent prefix, I'm thinking "dbms", e.g., "dbms:csv:foo“.

You can’t - because there is no „foo“ database for DBD::CSV at the moment.
Conceptual issue. In current state of development, those pure-perl DBMS
simulating drivers have no persistent metadata as mysql and postgresql have.

> * Do I have the metadata wrong for any of the DBMSes I have so far added support for? Right now that’s just the ports they listen on by default:
> 
> https://github.com/theory/uri-db/blob/master/t/db.t#L9

I think you miss my point - I don’t say that you’re wrong, I say you
lack a lot of requirements. When you don’t intend to support those
pure-perl drivers, you’re fine and please go ahead. When you intend
full DBI driver support, DBDI (https://github.com/timbunce/DBDI) could
enlighten you. Following that concept would allow you a migration to p6
one fine day ;)

Cheers
-- 
Jens Rehsack
[email protected]