]> granicus.if.org Git - postgresql/commit
Add support for coordinating record typmods among parallel workers.
authorAndres Freund <andres@anarazel.de>
Fri, 15 Sep 2017 02:59:21 +0000 (19:59 -0700)
committerAndres Freund <andres@anarazel.de>
Fri, 15 Sep 2017 02:59:21 +0000 (19:59 -0700)
commitcc5f81366c36b3dd8f02bd9be1cf75b2cc8482bd
tree8670bbca7404426515b5556ab2c6477b316e3edc
parent9b6cb4650bc6a56114000678c1944afdb95f8333
Add support for coordinating record typmods among parallel workers.

Tuples can have type RECORDOID and a typmod number that identifies a blessed
TupleDesc in a backend-private cache.  To support the sharing of such tuples
through shared memory and temporary files, provide a typmod registry in
shared memory.

To achieve that, introduce per-session DSM segments, created on demand when a
backend first runs a parallel query.  The per-session DSM segment has a
table-of-contents just like the per-query DSM segment, and initially the
contents are a shared record typmod registry and a DSA area to provide the
space it needs to grow.

State relating to the current session is accessed via a Session object
reached through global variable CurrentSession that may require significant
redesign further down the road as we figure out what else needs to be shared
or remodelled.

Author: Thomas Munro
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/CAEepm=0ZtQ-SpsgCyzzYpsXS6e=kZWqk3g5Ygn3MDV7A8dabUA@mail.gmail.com
12 files changed:
src/backend/access/common/Makefile
src/backend/access/common/session.c [new file with mode: 0644]
src/backend/access/common/tupdesc.c
src/backend/access/transam/parallel.c
src/backend/storage/lmgr/lwlock.c
src/backend/utils/cache/typcache.c
src/backend/utils/init/postinit.c
src/include/access/session.h [new file with mode: 0644]
src/include/access/tupdesc.h
src/include/storage/lwlock.h
src/include/utils/typcache.h
src/tools/pgindent/typedefs.list