pgsql: Enlarge bit-space for MemoryContextMethodID

From: David Rowley <drowley(at)postgresql(dot)org>
To: pgsql-committers(at)lists(dot)postgresql(dot)org
Subject: pgsql: Enlarge bit-space for MemoryContextMethodID
Date: 2024-04-07 11:32:47
Message-ID: E1rtQlT-000xzy-BY@gemulon.postgresql.org
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Enlarge bit-space for MemoryContextMethodID

Reserve 4 bits for MemoryContextMethodID rather than 3. 3 bits did
technically allow a maximum of 8 memory context types, however, we've
opted to reserve some bit patterns which left us with only 4 slots, all
of which were used.

Here we add another bit which frees up 8 slots for future memory context
types.

In passing, adjust the enum names in MemoryContextMethodID to make it
more clear which ones can be used and which ones are reserved.

Author: Matthias van de Meent, David Rowley
Discussion: https://postgr.es/m/CAApHDvqGSpCU95TmM=Bp=6xjL_nLys4zdZOpfNyWBk97Xrdj2w@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/0ba8b75e7ea6b7b3090c81239ebcb866772a624b

Modified Files
--------------
src/backend/utils/mmgr/README | 21 ++++++++++------
src/backend/utils/mmgr/mcxt.c | 43 ++++++++++++++++----------------
src/include/utils/memutils_internal.h | 18 +++++++++----
src/include/utils/memutils_memorychunk.h | 32 ++++++++++++++++++------
4 files changed, 72 insertions(+), 42 deletions(-)

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