Re: proposal: condition blocks in psql

Hi,

On 06/28/2015 08:01 AM, Pavel Stehule wrote:
>
> you can use PL/pgSQL - but there are some limits
>
> * maintenance large plpgsql functions
>
> * the plpgsql functions or anonymous functions create a transaction
> borders - what should not be wanted

But why is that a problem? Generally (sub)transactions are a good thing, 
but if you want, you may create one huge function. If you want to 
modularize this a bit, you may split that into multiple functions, but 
that's an option, not a requirement.

>
> * I cannot to use psql variables simply in plpgsql code (plpgsql has
> not any macro language) - so some patterns are implemented in plpgsql
> less readable
>
> for example, if you can create a script that create some plpgsql
> function for specified PostgreSQL version, then using PLpgSQL for this
> purpose is suboptimal due less readability and maintainability

I don't really see how a block of PL/pgSQL code is less maintainable 
than a similar block of code written in a pseudo-scripting language 
specific to psql. Actually I'd expect exactly the opposite, as PL/pgSQL 
has neat features like exception handling and such, which is completely 
absent in psql, or proper variables, which is somehow mimicked by 
session variables in psql.

If you really need to do the scripting outsite PL/pgSQL, there's plenty 
of suitable tools for that purpose IMHO. Starting with bash, or 
languages like Perl or Python.

And I think the same about readability ...

--
Tomas Vondra                   http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services