Re: need a function to extract list items from pg_node_tree

On 2012-12-21 07:20:00 -0500, Peter Eisentraut wrote:
> In order to implement the PARAMETER_DEFAULT column in the information
> schema I need a way to get the expressions out of the proargdefaults
> column.   pg_get_expr(proargdefaults, 0) gives me all expressions
> comma-separated, but I need them individually.  I think a function like
> pg_get_list_nth (to keep consistent with the internal list API) could
> work.  Alternatively, a list-to-array function might do the trick.  Are
> there are any other potential uses cases that should be considered here?
> AFAICT, indexprs is the only other system catalog column that contains
> an expression list.

Hm. Wouldn't it be better to create a pg_node_tree[] and use that in
pg_attribute? Its already in the variable length part of pg_proc
anyway...

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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