On 5/29/15 10:21 AM, Peter Eisentraut wrote:
On 5/28/15 10:15 PM, Craig Ringer wrote:
I was a puzzled by src/backend/utils/fmgr/README and fmgr.h's
descriptions of fcinfo->flinfo->fn_extra (FmgrInfo.fn_extra) as they
seem to conflict with actual usage.
The docs suggest that fl_extra is for the use of function call handlers,
but in practice it's also used heavily by function implementations as a
cache space.
The documentation could also be updated about this. It mentions using
fn_extra for PL handlers, gist functions, and set-returning functions,
but it doesn't say that you can use it any old function for anything you
want.
I'm not sure how up to date that README actually is. It looks more like
a historical document describing the original proposal.
FWIW, I think it'd be good to also document what lifetime you can expect
out of something in fn_extra. I realize you can figure it out from
fn_mcxt, but I don't know that that's terribly obvious to others.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Data in Trouble? Get it in Treble! http://BlueTreble.com
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