Обсуждение: RowDescription via the SQL?
Hi, It's possible to query pg_prepared_statements view to obtain the information about parameters used in the statement that was prepared. But I don't found how to get the information about the rows that will be returned when the statement is eventually executed. (It's possible to get this information via the frontend/backend protocol as a response on the Describe.) But out of interest, is it possible to get such information via the SQL? -- // Dmitry.
On Thu, Jun 2, 2016 at 1:14 AM, Dmitry Igrishin <dmitigr@gmail.com> wrote: > Hi, > > It's possible to query pg_prepared_statements view to obtain the > information about > parameters used in the statement that was prepared. But I don't found > how to get the > information about the rows that will be returned when the statement is > eventually executed. > (It's possible to get this information via the frontend/backend > protocol as a response > on the Describe.) But out of interest, is it possible to get such > information via the SQL? hm. what's the use case? and, what's the definition of "eventually"? merlin
2016-06-03 1:55 GMT+03:00 Merlin Moncure <mmoncure@gmail.com>: > On Thu, Jun 2, 2016 at 1:14 AM, Dmitry Igrishin <dmitigr@gmail.com> wrote: >> Hi, >> >> It's possible to query pg_prepared_statements view to obtain the >> information about >> parameters used in the statement that was prepared. But I don't found >> how to get the >> information about the rows that will be returned when the statement is >> eventually executed. >> (It's possible to get this information via the frontend/backend >> protocol as a response >> on the Describe.) But out of interest, is it possible to get such >> information via the SQL? > > hm. what's the use case? It's about consistency. It's possible to prepare the statement either via SQL and fe/be protocol , it's possible to get the information about parameters of prepared statement either via SQL and fe/be protocol, but getting the information about the resulting rows is only possible via the fe/be protocol. > and, what's the definition of "eventually"? I borrowed this definition from here https://www.postgresql.org/docs/9.6/static/protocol-flow.html#PROTOCOL-FLOW-EXT-QUERY (The Describe message (statement variant) ...) -- // Dmitry.