pgsql: Do not emit WAL for unlogged BRIN indexes

Do not emit WAL for unlogged BRIN indexes

Operations on unlogged relations should not be WAL-logged. The
brin_initialize_empty_new_buffer() function didn't get the memo.

The function is only called when a concurrent update to a brin page
uses up space that we're just about to insert to, which makes it
pretty hard to hit. If you do manage to hit it, a full-page WAL record
is erroneously emitted for the unlogged index. If you then crash,
crash recovery will fail on that record with an error like this:

FATAL: could not create file "base/5/32819": File exists

Author: Kirill Reshke <reshkekirill(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/CALdSSPhpZXVFnWjwEBNcySx_vXtXHwB2g99gE6rK0uRJm-3GgQ@mail.gmail.com
Backpatch-through: 14

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/951b60f7abdcdeb37f2d73ad4822f278d2687c1c

Modified Files
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src/backend/access/brin/brin_pageops.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)