[HACKERS] Stateful pointers in set-returning functions
Hi, I'm writing a set-returning function which places a file handle into PG's FuncCallContext's user_fctx space. My problem is that when the function is ran with a limit clause (SELECT * FROM foo() LIMIT 10) the server will stop calling the function automatically, not giving me a chance to close the file handle. Is there a way to get the limit value inside of foo() and set the max max_calls parameter correctly? Thanks, Ian -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Stateful pointers in set-returning functions
Ian Pye ian...@gmail.com writes: I'm writing a set-returning function which places a file handle into PG's FuncCallContext's user_fctx space. My problem is that when the function is ran with a limit clause (SELECT * FROM foo() LIMIT 10) the server will stop calling the function automatically, not giving me a chance to close the file handle. Is there a way to get the limit value inside of foo() and set the max max_calls parameter correctly? No, and even if there were, this would be a very unsafe practice, since errors or other issues could result in early termination of the query. You would likely be better off using tuplestore return mode so that you can do all the reading during one call and not have to assume that you'll get control back again. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Stateful pointers in set-returning functions
Fair enough -- thanks for the tip. On Thu, May 24, 2012 at 11:21 AM, Tom Lane t...@sss.pgh.pa.us wrote: Ian Pye ian...@gmail.com writes: I'm writing a set-returning function which places a file handle into PG's FuncCallContext's user_fctx space. My problem is that when the function is ran with a limit clause (SELECT * FROM foo() LIMIT 10) the server will stop calling the function automatically, not giving me a chance to close the file handle. Is there a way to get the limit value inside of foo() and set the max max_calls parameter correctly? No, and even if there were, this would be a very unsafe practice, since errors or other issues could result in early termination of the query. You would likely be better off using tuplestore return mode so that you can do all the reading during one call and not have to assume that you'll get control back again. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
