Обсуждение: pgsql: Update comments on rd_newRelfilenodeSubid.

Update comments on rd_newRelfilenodeSubid.
Ensure comments accurately reflect state of code
given new understanding, and recent changes.
Include example code from Noah Misch to
illustrate how rd_newRelfilenodeSubid can be
reset deterministically. No code changes.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/c2b32180649fe9105e784ad0519fe243605f78a3

Modified Files
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src/backend/commands/copy.c |   21 +++++++++++++++------
src/include/utils/rel.h     |   13 +++++++++++--
2 files changed, 26 insertions(+), 8 deletions(-)