2011/10/11 Merlin Moncure <mmonc...@gmail.com>: > On Tue, Oct 11, 2011 at 3:40 AM, Pavel Stehule <pavel.steh...@gmail.com> > wrote: >> Hello >> >> A current limits of dynamic work with row types in PL/pgSQL can be >> decreased with a possible casts between rows and arrays. Now we have a >> lot of tools for arrays, and these tools should be used for rows too. >> >> postgres=# \d mypoint >> Composite type "public.mypoint" >> Column │ Type │ Modifiers >> ────────┼─────────┼─────────── >> a │ integer │ >> b │ integer │ >> >> postgres=# select cast(rmypoint '(10,20) as int[]); >> array >> ──────────── >> {10,20} >> (1 row) >> >> postgres=# select cast(ARRAY[10,20] AS mypoint); >> mypoint >> ───────── >> (10,20) >> (1 row) >> >> What do you think about this idea? > > Not sure what it buys you over the syntax we already have: > > select row(foo[1], bar[2]); > select array[(bar).a, (bar).b];
You can do it manually for known combinations of rowtype and arraytype. But proposed casts do it generally - what has sense mainly for plpgsql functions or some sql functions. > > Also, in my coding of composite types, homogeneously typed rows don't > really come up that often... you can use everywhere text type. When I wrote http://stackoverflow.com/questions/7711432/how-to-set-value-of-composite-variable-field-using-dynamic-sql/7722575#7722575 then I had to do lot of string operations. Proposed casts significantly do this simply - and it is enought general for general usage. Pavel > > merlin > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers