Re: [Ruby-DBI-devel] Array support for DBD::Pg

[Michael N. <mne...@nt...>]

On Wed, May 14, 2003 at 05:57:09PM +0200, Oliver M. Bolzer wrote:
> Hi!
> 
> Currently, DBD::Pg does not support PostgreSQL's native Array types as
> described in
> http://www.postgresql.org/docs/view.php?version=7.3&idoc=0&file=arrays.html
> 
> Attached are two patches that add support for
> - reading of Arrays
> - quote()ing of Arrays
> 
> I have submitted the reading-part before, but did not receive any response
> at that time. Seems like nobody is using PostgreSQL's arrays, except me :-)
> I'd really appreciate some kind of comment from the DBD::Pg maintainer.

Sorry, I had not much time in the last months. 
There is currently no active DBD::Pg maintainer (is there?). 

I'd be really happy if someone would take over this part, so I could
concentrate (i.e. spend my time) more with overall DBI issues.

What I really had in mind is, to completely separate the DBDs from the DBI
(= different projects). Doing this, updates on single DBDs
would come out much quicker than today it's the case.

> Now let me explain the patches:
> 
> pg_array_quote.diff:
> 
> PostgreSQL-Arrays are surronded by single quotes, the array delimiters
>  are{ and }, the elements separated with comma. The problem is, that inside
> the array, different quotingrules apply than usual. E.g. a Strings and Dates
> are quoted with double-quotes instead of the usual single-quotes. Additionally,
> all ' and \ must be extra escaped because the array as a whole is handled as
> String in SQL.
> 
> To cope with this, an extra private function quote_array_elements() is added
> to quote array-elements. This method is called from quote(), when the object
> to be quoted is an Array.
> 
> The patch is based on Pg.rb 1.27 . I just discovered that in 1.28, support for
> PGconn.quote was added. But the quoting of Arrays of PGconn.quote is WRONG.
> So slight modifications would be additionally needed to bypass PGconn.quote if
> the value is an array and use my quoting mechanism instead. 

Can you try the patch with the newest version (1.31) of Pg.rb and tell me if
there are any modifications (i.e. send me the updated patch).

> pg_array.read.diff:
> 
> The goal is to get an array of the respectable type returned by DBD::Pg instead
> of Strings like "{1,2,3}" when selecting a column with an array-type.
> For this I've improved load_type_map() to register array-types and the type of
> their elements. Entries with an _ in front of them are actually arrays, according
> to the PostgreSQL documentation.

I thought types with prefixed _ are basic Postgres types.
Removing the _ types from the type_map do not break programs?

Regards,

  Michael