pgsql-server/ oc/src/sgml/runtime.sgml rc/back ...

CVSROOT: /cvsroot
Module name: pgsql-server
Changes by: momjian@postgresql.org 03/03/19 23:51:44

Modified files:
doc/src/sgml : runtime.sgml
src/backend/postmaster: postmaster.c
src/backend/utils/init: miscinit.c
src/backend/utils/misc: guc.c postgresql.conf.sample
src/include : miscadmin.h

Log message:

I can see a couple possible downsides: (a) the library might have some
weird behavior across fork boundaries; (b) the additional memory space
that has to be duplicated into child processes will cost something per
child launch, even if the child never uses it. But these are only
arguments that it might not *always* be a prudent thing to do, not that
we shouldn't give the DBA the tool to do it if he wants. So fire away.

Here is a patch for the above, including a documentation update. It
creates a new GUC variable "preload_libraries", that accepts a list in
the form:

preload_libraries = '$libdir/mylib1:initfunc,$libdir/mylib2'

If ":initfunc" is omitted or not found, no initialization function is
executed, but the library is still preloaded. If "$libdir/mylib" isn't
found, the postmaster refuses to start.

In my testing with PL/R, it reduces the first call to a PL/R function
(after connecting) from almost 2 seconds, down to about 8 ms.

Joe Conway