For now it consists of only:
using int128_t = __int128;
using uint128_t = unsigned __int128;
All new privitive data types should go into this file in the future.
v5 (current) version of the extent map supports int128_t min/max
values. This commit provides upgrade capability to load_brm program
that when reads an extent map saved to disk earlier with save_brm,
with a EM_MAGIC_V4 entry, converts it to the current v5 "wider"
extent map.
If the plugin is restarted after the system is running, it's possible to have stale references to shared memory. This patch deletes those references so the next time they're used, just-in-time initialization will get the latest.