Re: proposal: row_to_array function

2015-01-16 18:42 GMT+01:00 Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>:

> On 1/16/15 11:22 AM, Pavel Stehule wrote:
>
>>
>>
>> 2015-01-16 18:03 GMT+01:00 Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com <mailto:
>> Jim(dot)Nasby(at)bluetreble(dot)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.
>

what do you think? How this can be implemented?

>
> 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 it either. 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
>