Обсуждение: TupleDesc and HeapTuple
Hi, I don't see any direct link between the TupleDesc structure and the HeapTuple one, and it seems strange to me since to manipulate a tuple you often need the descriptor. What is the trick here? Thanks, Luca
Excerpts from Luca Ferrari's message of mar jul 06 02:53:03 -0400 2010: > Hi, > I don't see any direct link between the TupleDesc structure and the HeapTuple > one, and it seems strange to me since to manipulate a tuple you often need the > descriptor. What is the trick here? You're supposed to know which relation you got the HeapTuple from, so you get the TupleDesc from there.
On Tuesday, July 06, 2010 09:58:45 pm Alvaro Herrera's cat walking on the keyboard wrote: > You're supposed to know which relation you got the HeapTuple from, so > you get the TupleDesc from there. True, but if I want to pass the heaptuple around I must pass also its tuple desc, or the receiver will not know how the tuple is composed. Maybe this case never happens/happened. Luca
2010/7/7 Luca Ferrari <fluca1978@infinito.it>: > On Tuesday, July 06, 2010 09:58:45 pm Alvaro Herrera's cat walking on the > keyboard wrote: >> You're supposed to know which relation you got the HeapTuple from, so >> you get the TupleDesc from there. > > True, but if I want to pass the heaptuple around I must pass also its tuple > desc, or the receiver will not know how the tuple is composed. Maybe this case > never happens/happened. > In pg core - receiver have to have actual datatype everywhere - so if you write a some general function, then you put a Datum value - universal PostgreSQL datatype and you have to put a datatype identification - Oid, typmod or TupleDesc. Pavel > Luca > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general >