Re: proposal: row_to_array function

On 1/16/15 11:22 AM, Pavel Stehule wrote:
>
>
> 2015-01-16 18:03 GMT+01:00 Jim Nasby <Jim.Nasby@bluetreble.com <mailto:Jim.Nasby@bluetreble.com>>:
>
>     On 1/16/15 3:45 AM, Pavel Stehule wrote:
>
>         I am returning back to processing records in plpgsql.
>
>         I am thinking so it can be simply processed with transformations to array.
>
>         Now we have similar functions - hstore(row), row_to_json, ... but using of these functions can be a useless
step.Any row variable can be transformed to 2D text array.
 
>
>
>     How is it useless? Why wouldn't you just use JSON and be done with it?
>
>
> We can use a FOREACH IN ARRAY iteration in plpgsql (second variant is a implementation FOREACH for jsonb)
>
> so ROW->ARRAY is shorter than ROW->JSON->ARRAY or ROW->HSTORE->ARRAY

I think the real problem here is that we're inventing a bunch of different ways to do the same thing: iterate over a
set.Instead of doing that, should we add the idea of an iterator to the type system? That would make sense for arrays,
hstore,json and XML.
 

>     Do you have some use cases you can share?
>
>
> processing of NEW, OLD variables in triggers

Note that last time I checked you couldn't do something like NEW.variable, and I don't think you could use EXEC to do
iteither. So there's more needed here than just converting a record to an array.
 

>         There two possible transformations:
>
>         row_to_array --> [[key1, value1],[key2, value2], ...]
>         row_to_row_array --> [(key1, value1), (key2, value2), ... ]
>
>
>     If we're going to go that route, I think it makes more sense to create an actual key/value type (ie:
http://pgxn.org/dist/pair/doc/__pair.html<http://pgxn.org/dist/pair/doc/pair.html>) and return an array of that.
 
>
>
> ok
>
>     --
>     Jim Nasby, Data Architect, Blue Treble Consulting
>     Data in Trouble? Get it in Treble! http://BlueTreble.com
>
>


-- 
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com